surging/stalling

[captluv]

Ok guys, check this one out. Recently, I've cleaned out the throttle body because the car (96 I30) was stalling out at red lights. So, now about a month and a half or so after the cleaning, the car's started stalling again, and if that wasn't bad enough, it's surging or dropping rpm's at around 1500 rpms. What will happen is I will hit the gas after slowing down and the rpm's drop really low, lower than they should be and even if I step on the gas harder, it takes a few seconds for the engine to pick back up.

As if all that wasn't aggravating enough, on the freeway, running at a constant speed, sometimes the rpm's will drop, then jump back up sharply causing the car to buck a little. I'm thinking dirty intakes/IACV or maybe failing TPS? The TB is clean, so I can't imagine that's the problem, anyone have any ideas? Any help is appreciated, thanks.

[02maxSE]

Question, due you have a CAI on there? I had that problem with my 97' when first installed the CAI come to find out i need to re-route my breather hose.

[captluv]

Not sure what a CAI is but the car is completely stock if that's what you're asking.

[02maxSE]

CAI is cold air intake. sorry i can't help. all i can think of is maybe the fuel injectors, fuel pump, a lose breather hose, or something electrical. try AutoZone if you have one in your area they do free read outs of the computer.

[coolhand]

Also, it could be your MAF (Mass Air Flow) sensor. My 89 was doing the same thing until I replaced it.

[maxhopper]

The problem you are describing would lead me to clean the idle air control valve first. http://www.moodym.com/maxima/c...l#IAC

If that didn't fix the problem, I would clean the MAF. zerothread?id=182442

And if that doesn't help, I would look at the EGR valve passages being clogged, or the EGR valve being bad.

[dr-rjp]

I would give a "Ditto" on the IACV, except for the fact that your car is surging on the highway and dropping RPM's suddenly.

THAT sounds like an electrical/electronic problem which goes well beyond the role of the IACV (the IACV controls idle speeds). I'd look at the other parts of the engine management system first, like your temperature sensors (air and coolant).

HOWEVER, even before going there, I would begin with checking your ignition coils!

If you have one that is operating intermittently, that will cause all of the problems you listed. BUT HERE'S A SURPRISE: YOU COULD HAVE AN ELECTRICAL SHORT SOMEWHERE.

Have a mechanic check out your electrical system. I'd bet a dollar to doughnuts that you have a short somewhere.

iF IT ISN'T A SHORT, THEN MY MONEY IS ON A BAD COIL.

[captluv]

Thanks, guys, for all the suggestions. Now, from what I've read, I'm leaning toward a bad coil as well, but I've got no CEL, so do I have to wait until the coil goes bad enough to set off a code to find out which one it is? My gas mileage has gotten pretty bad compared to what it used to be so that's another factor to consider.

Also, I know the knock sensor going bad is another common problem. Could this be caused by a failing KS as well?