Hey all...ultra newbie here. Looking for any thoughts/advice/suggestions/etc. for my buddy's idle problem. Truck's running great and road trip to Charleston to coach my soccer team. Getting ready to come back, vehicle's running fine, stop to tank up, re-start, and something is very wrong. Noticed an idle fluctuation when stopped with clutch depressed with RPMs going from 1000-3000. Rev'd it, and idle went back into a "more normal" state. Got on the interstate and my trusty ride brought me back home safely. Had to stop for fuel and the idle problem continued. This was on Sunday. Didn't start the vehicle yesterday...too depressed...plus, it was raining. Cranked it today...idle went to 1000 and every 15 secs...approx....something "clicked" in the bay, and it upped to about 1500. It never stabilized and "eased" into a very rough mode...not violent, but definitely not smooth, as before. I'll take any help. Much thanks in advance. -Gary

 

Any codes? CEL on? I would try cleaning the MAF first.. might be the IAC (Idle Air Control valve).. others that are smarter and more handsome should be along soon..

 

I haven't accomplished any computer diagnostics yet. No check engine light...just very not normal. It's raining again today, so I'm going to try checking in the bay tomorrow, for any obvious problems. This is uncool...this truck has been my buddy through thick and thin...I hope I can find out what's going on. Thanks for the suggestion. I'll check it out.

 

What engine do you have. How many miles and what maintenance has been done.

 

Sounds like bad fuel??? It didnt happen until after you filled up. Try some heet in the tank??
For water removal.

 

Sorry...4.6L...just rolled over 100K. Only changes from bone stock are filters, belts, and battery...no hoses. On the fuel thought...I actually had 3/4 of a tank...I just wanted to top off. I wouldn't think that it would have that kind of instant negative effect so quickly. Could be, though...I'll try the Heet, also. Question...and I know this is asking for a reach...does this sound like a vacuum problem? Thanks.

 

Clean or replace the IAC.