Cannot rev past 2k rpm when hot??

[sidewinders13]

hello gang, i have a 1992 nissan 240sx with a KA24de. i been having a big problem lately with the car, when i get up in the morning to start the car and then drive off, its perfectly fine but driving into 15min of time the cars rpm needle bounces like crazy and then stuttering and not letting me rev past 2k rpm or sometimes not even past 1500rpm. i can let the car sit for say 15min and then start it up and it will be fine but then again once it gets hot then everything acts up and rpm needle goes nuts. if i was to keep the gas pedal pinned down during this time, i get like misfiring and hear it thru the filter and its like a fuel cut. i changed the ignition module to see if that would help but nothing, i dont know what else to do and no one has an answer to this problem in my area, if anyone has a answer or can help me, please do and appreciate your time and efforts. BTW: i also have a good freind of mine whos going thru the same situation with his sr20det and he changed the maf, ignitor chip and same exact problem still, im really clueless on what can cause this madness

[NISTECH]

On your ka I am thinking cap and rotor as the most likely cause, second thought is restricted exhuast.

[sidewinders13]

thanks for the fast reply, i have a stock cat back exhaust and i changed the cap anf rotor but still the same prob, now its not letting me rev past 1500rpm and when i gas it, it will bog and fuel cuts at 1500 rpm. im stumped

[NISTECH]

get a fuel pressure gauge on it and see if your losing fuel pressure when the incedent occurs.

[sidewinders13]

thanks again, yea that was going to be my next step when the problem occurs. some have told me it sounds like a distributor problem but i rather check the fuel pressure b4 spending any more money. thanks and i will post back with an update.

[sidewinders13]

update.....i didnt get my hands on a fuel pressure gauge yet but now my rpm limit is 1k rpm, seems like it drops 500rpms as the problem persists and then gets worse cause it went from 2k to 1500 and now down to 1k rpm, this is really bugging me out and making me want to sell this car since i have no clue on what it really is, any more suggestions? thanks in advance

[Touchdown038]

This really does sound like a clogged exhaust... you said it's stock? It's possible then.

[NISTECH]

Throw a vaccum gauge on it and rig it up so you can see it when it acts up. When you got it floored that vaccum gauge should read less then 5 "hg. If it reads in the neighborhood of 15" hg you got restricted exhaust.