My max (96 SE, Auto, 102K) still idles rough after doing all of the following....none of which improved the idle at all (though the starting is nearly instant now). the idle speed stays fairly constant...but the engine is not its buttery smooth self until you get on the pedal. At times the roughness can be rather severe, actually making the interior of the car rattle.

- New NGK's
- New fuel filter
- Cleaned TB and intake
- A couple bottles of fuel system cleaner
- One O2 sensor kept through codes (front left)

I cleaned and tested the IAC valve, and had no resistance across 3-4...which according to the Haynes manual is a failure. best price I found on an IAC valve was $132+ship.

The car starts and runs great, good power every where, mileage is tpyically mid 20's. The only driveability comment is that when you let off the gas to coast, the engine really seams to drag you down quickly. Power steering and AC fast idle valves are working. The only other thing(s) I can think of is checking ignition coils, or perhaps fuel injectors....but with either of those wouldn't I notice generally decreased performance/mileage, poor starting....etc...?? Maybe EGR valve..?..but that should throw a code if its sticking.

thanks for your input.

 

Whats your idle speed in neutral and in drive?

 

Have you checked the PCV valve. It is a one way valve, if you take it off and you can blow through it and it closes when you inhale air through it, then it works. It is a pain to get to. It is on the top of the valve cover near the throttle body.

 

I have a 96 SE Auto with 125K and have exactly the same problems. My IAC's were both good, but I still suspect the Steering one is bad - going to recheck soon. I get the shakes during certain periods of acceleration. Could it be a valve problem?