My car doesn't like to idle at the normal almost half the time. It will stick around 900, then make its way up to 1500 and stay there for a good 10 seconds, then drop back down for a few seconds, then go back up. If I tap the gas a little, I have a slight chance it will go back to normal idling RPM. Not sure what to think.

info on my 91 SE 5spd:
156k,
new vacuum lines,
used injectors from a wrecked max with 89k,
new NGK standard spark plugs,
plug wires and distributor about 20k old,
cleaned MAF sensor,
new O2 sensor,
Chevron Techron fuel system cleaner used every oil change

I am not sure whats causing the idle to fluctuate like this. Can anyone help?

 

I have the same problem... been doing that for some months now. I learned that if you turn on the AC it will drop rpm's to about 8-900 since the ac system is driven by the belt... (don't remember the eng word!) anyways, that works

not satisfying though, I too would like to know what the problem is... I belive it to be either the fuel injectors (having a bit of a problem with them) or the fuel mixture somehow, rather than an electrical problem.

 

"fuel system cleaner"
- Have you read the Nissan TSB of cleaners? They say that one should not use them... see:
http://maxima.theowensfamily.com/tsb

- Have u cleaned IACV idle control valve assy & throttle assy? If not, by now systems are choked of microcarbon particles that seep through filter.

- TPS check, replacement?
see also MAF at: http://www.parttrackers.com/library/1/

- Wires: copper wires or carbon fiber ? pudding... latter ones do not work even new as powder in a tube has never been a good conductor. Yes they're good at damping static - cause they dampen sparks also. Some NGK and some others that include also wire, maybe good. Will never test.

COPPER is the only higway for electrons to race. Just COPPER! And youre better off than with the baked sixpack coils...