I have a 99 Explorer with the 4.0 OHV engine and it has 167,000 miles on it. It has a rough idle when sitting and if it has sit for a while and you try to start it it acts like it is not going to start then it kinda stutter starts. if it was just running and you start it back up it starts fine. I just did a tune up on it spark plugs and wires and its still doing it. Any ideas on how I can fix this?

Thanks

 

I have that same problem with the same year, same engine, but my mileage is about 115,000~.. It's pretty frustrating. I'm thinking the low idle control valve may be the issue with mine, I've done a full tune up (plugs wires, oxygen sensors, injectors. fuel filter.) Mines kind-of rough, but not too rough, but it runs like a top when it warms up.

 

[quote]ORIGINAL: gettin2ndgear

I have a 99 Explorer with the 4.0 OHV engine and it has 167,000 miles on it. It has a rough idle when sitting and if it has sit for a while and you try to start it it acts like it is not going to start then it kinda stutter starts. if it was just running and you start it back up it starts fine. I just did a tune up on it spark plugs and wires and its still doing it. Any ideas on how I can fix this?

Thanks

Did your check engine lite come on @ any time?

 

Either it's the IAC valve or the intake gaskets. If you change the intake gaskets change both upper and lower at the same time. Don't ask how I know. LOL

 

Sounds like the idle air control motor. It's bolted on the top of the intake, near the throttle body and is easy to remove. You can clean it with some choke cleaner and it will improve the operation of it. If that helps, then you know you need to replace it, probably before winter really sets in.