Surging Idle seems to be a generic symptom of 4ZE1 motors provoked by any number of underlying problems. It is difficulty to distinguish between the problems when they throw such similar symptoms, so beware applying solutions directly that worked for others without troubleshooting your particular motor.

I have seen very similar cyclic revving/surging present from as varied causes as worn/out-of-adjustment throttle body, dirty MAF, tired air solenoids, out-of-adjustment throttle stop, and more. Worse yet, this condition seems often to be transient, presenting only in certain ambient temperatures, under certain engine temperatures. <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> Frustrating! <img src="/forums/images/graemlins/baby.gif" alt="" />

I think many folks end up frustrated by this every-occasional general symptom, and wind up just coping with it until it fades away... That's not to say it isn't worth trouble-shooting, but it can be a bugger to find the actual cause.

Randii