OK well let me start by saying I'm only writing this topic right now to try and help other people with the same problem as the one I just went through. I have actually solved the problem before writing this so this is simply to help others with the same issue

1999 nissan pathfinder 202K miles.
I'll try to be brief but have to sort of give the history so everyone understands what happened.

tranny went out. had it rebuilt for about $3200 yikes! got it back and within a couple days noticed that only in overdrive the rpms seemd to bounce at around 2500 rpm. sort of felt like the truck was thinking about downshifting but then changed its mind. so it did it intermittently but constand enough to be VERY ANNOYING. no other problems. ran and idled great! all other gears seemed fine.
after a few days I get a CEL i code read it to be p0325 Knock sensor and p706 (or something) "transmission range circuit low input" and another symptom surfaces. it wont shift into overdrive. bring it right back to tranny shop. *under warranty* they tell me I have to fix the knock sensor first before theyll do anything, becasue the knock sensor could make it not go into overdrive.
at this point im pissed becasue I think they're just jerking me around and the knock sensor on these 3.3l is deep under the manifold. so I find a nice forum on how to relocate it using a maxima sensor and harness. saves about 9 hours but doesn't seem like the knock sensor is in the best location to detect knock after reloaction, but whatever thats another story and saves 9 hours .
so knock sensor relocated cleared code and back to tranny shop with overdrive still out. aftr 2 days they fixed it by changing the neutral safety switch, (transmission range sensor) this sensor was causing it to think it was in the wrong gear and wouldn't shift into overdrive because of it.. so since it was under warranty no charge YAY!
driving home I notice the rpms still bouncing and sort of bucking in overdrive, DAM, now I'm mad becasue I already brought truck back twice and its still messed up WTH.
so a few days go by and the bucking hesitation gets worse, not it does it in every gear sometimes stalls at idle and very difficult to drive, strange thing is is starts up fine and runs fine for about 5-10 minutes then starts the bucking very gently until it becomes out of hand... no CEL but I do find a code pending for "p1336 crankshaft/camshaft sensor" so cheapest easiest part is the crankshaft sensor $50 (on the driverside top of bellhousing) pull 4wd driveshaft down and easy swap for the sensor.. problem remains ARGHHH!
tear apart distributor becasue cam sensor is part of distributor. AH HA find metal chunks all up under the plastic cover under the rotor, look closer, the distributor bearing had totally exploded. so off to the parts store, $300 later for new distributor with igniton module. and about an hour later truck runs AWESOME. so I swapped the crankshaft sensor back to old one for my $50 back and still truck runs great!!!! YAY!!!

moral of the story I wouldve bet my right arm the tranny was the problem since at first it only had bucking issues in overdrive, and happended right after tranny rebuild. but in the end somethng completely unrelated WOW so invest in a ODBII computer worht their weight in gold! if you get the crankshaft/camshaft sensor code popping don,t jump the gun and go for the cranksahft sensor, check inside the distributor and remove the plastic plate under the rotor, inspect the bearing takes about 10 minutes to checkout visually. then decide.. YAY hope this helps some folks I was sort of stumped for a while

O yes!!! Forget those dumb a** codes.....knock sensor BS!! Tear down distributor and look for metal shavings inside. you will also be missing several bearings! I got a new Duralast gold distributor from auto zone $241 total cost (lifetime warranty) andinstalled it, problem solved! Truck runs great I have a 3.3l Frontier XE 4x4 and it started acting up about 180,000 miles

I recently had a similar experience with my ‘96 Pathfinder 3.3L. 187k miles.

SYMPTOMS: car starts up in morning, and runs fine for 10 min. Then idle becomes very rough. When driving, intermittent but frequent loss of power accompanied by frequent “bucking”/jerking. Stalls at idle, but always restarts easily. Smoky exhaust. No OBd codes or CEL!

Diagnostic steps:

1) FUEL: suspected water in gas. Disconnected gas line at fuel rail and jumpered fuel relay to pump 5 gal into a Jerry can. Replaced fuel filter. - No improvement. Installed pressure gauge and tested fuel pressure per FSM procedure - right on spec. Ok, maybe it’s a bad injector. Used a mech stethoscope to listen for the click-click on each injector - all sounded OK. Tested coil resistance on each injector. All in spec. (did this by back probing injector wires at F101/F6 connector which is very accessible, since it’s near impossible to reach injectors under intake plenum). All injectors had a coil resistance in spec.
2) IGNITION: Pulled plug wires and used a spark tester to ensure each cylinder was getting good spark - all looked good. Strong spark. Plugs, contemplated pulling each and checking/replacing, but it’s a pain to vacuum/blow out each plug hole before removing plug. Besides, If a plug was bad, while did engine run good for first 10 min in morning? Push these further down the troubleshooting list. Checked ignition coil and power transistor using FSM procedure - in spec. Checked ignition timing. Tough to get accurate read, since idle was so unstable, but looked about 15 deg BTDC.
3) SENSORS: could this be a fuel ratio issue? Plugged in OBD scanner and observed ECU was in closed-loop control. Unplugged each fwd O2 sensor, and observed ECU switch over into open loop control. Idle remained rough/unstable. OK, so O2 sensors must not be the issue.. unplugged TPS sensor-no change. Unplugged MAF sensor-no change, idle remained rough. Maybe the Knock sensor is spuriously triggering the Ignition Retard system and throwing out ign timing? Disconnected knock sensor- no improvement. (Disconnecting knock sensor is tricky, since connector/sensor is deep behind engine. Instead, I disconnected the F6/F101 connector, and then built 8 little jumper-pins to re-establish continuity btw all terminal contacts. See photo. Fire-up engine, then remove the jumper for knock sensor. OBD should throw a knock-code if you’re doing it right). Anyway, no luck, wasn’t the knock sensor. Starting to run out of ideas…temptation grows to begin throwing parts at the problem! Reviewed Symptom Matrix Chart in FSM manual, EC chapter p.77. It notes that the camshaft position sensor should be inspected. Ok. Pulled distributor cap. While removing rotor, I noticed a little looseness in the rotor shaft. It was possible to wiggle shaft about 1/32” from side to side… removed rotor, and plastic shroud over camshaft sensor. Inspected slotted-plate on camshaft sensor-looked fine. Using a bright flashlight, I inspected BENEATH camshaft sensor plate, and noticed some metal fragments. I ran my pickup magnet down there, and pulled it back up to find two bearing balls attached to it. Ah ha! The bearing had exploded, creating looseness in the distributor shaft, and thus causing the camshaft position sensor to report erratic readings to the ECU.
4) THE FIX: So $120 later I had a new distributor on the doorstep (Cardone 84-58600). Installed next day, set ignition timing. Engine runs great!
5) AFTERTHOUGHTS: 18 months ago I was troubleshooting and intermittent misfire (eventually discovered bad fuel injector), and replaced the distributor cap. One of the points in the old cap had a scratch across it, indicating it had contacted the rotor. I wiggled the rotor around and noticed very slight play in the rotor shaft. Maybe 1/32” of play. I now believe this was the beginning of bearing failure. If I’d been more experienced, I may have identified this issue at the time, and proactively replaced the distributor. Live and learn…
6) ACKNOWLEDGMENTS: this forum is invaluable. If it wasn’t for this thread and ‘dochera’s’ post below, I wouldn’t have thought to inspect so carefully beneath camshaft sensor for bearing fragments. I’m very appreciative of this knowledge resource.

Yeah, mine suffered mechanical failure before camshaft sensor failure. Another issue that can happen with those distributors is the set screw that holds the rotor can work itself loose and can be misdiagnosed as a distributor failure. Loctite on set screw will prevent that. And this forum has also saved me a lot of time and money!