Engine idles up and down at stop and dies

[ATL_Mounty]

I have had this problem for a while now, when I come to a stop sometimes the engine revs up and down with out touching the gas and conks out sometimes. It does it with the tranny in gear or just in neutral. I thought it was the plugs so I replaced them, but still happens. It doesn't do it all the time but randomly when I am at a complete stop. Could it be a bad coil? I have also seafoamed the injectors thinking one of the was clogged. Or could it be from some of the performance upgrades: Mac CAI, Trickflow 70mm throttle body, Trickflow intake plenum, also flowmaster muffler. I was thinking the fuel filter could be causing this, I think it is the original one and I have 99K on it. I also checked the vac hoses when I installed the throttle body and plenum last weekend and they looked ok. Also it the 4.6 V8. Any help would be great I don't wifey driving it till I get this fixed....

 

[dogfriend]

If it isn't maintaining a normal idle speed, it is probably an issue with the IAC (idle air control) valve. They are notorious for causing issues on 2nd gen Explorers. If it is sticking closed, the idle speed will be too low and the truck can stall.

 

[jutgin]

TPS maybe? Is it throwing codes?

 

[ATL_Mounty]

It hasn't ever throw any codes is the weird thing. Can you clean the IAC valve or should I just replace it? Thanks for the help....

 

[dogfriend]

You can try cleaning it, but I replaced mine when it kept stalling when I put it in D. That was many years ago.

 

[ATL_Mounty]

I think I fixed it I changed the fuel filter and it hasn't done it again. It was the original one and I have 90k plus on it. When I turned the old one upside down brown and black liquid poured out it was nasty to think my car was running on that junk. Now its a beast with all the Trickflow parts I got for x-mas.... I can't keep my right foot out of it