No Fast Idle

[Jim C]

I have a 99 Explorer with a 4.0L Engine and Auto Trans. When I start the Explorer up the engine only fast idles for a few seconds and then the RPM's drop to the point where it almost wants to stall. My local repair shop replaced the IAC Motor but that did not fix the problem. This happens if the engine is cold or warm. Anyone else had this problem and maybe someone cane tell me what I should check next.

Thanks

[shorod]

You may have an EGR valve that is opening at idle, or not closing fully. This doesn't imply the EGR valve itself is bad. It may need to be cleaned, or the DPFE or EGR vacuum regulator could be faulty.

I'm assuming that your repair shop cleaned the IAC passages and throttle plate so that is not the problem.

Does the engine run smoothly if you just lay into the throttle a little bit?

-Rod

[Jim C]

Yes, idle is smooth if you give it some gas but at idle the RPM's tend to fluctuate. I was thinking it could be EGR too.