I had an interresting talk with a friend of mine today, He's a service writer at one of the Ford dealerships. I mentioned that every once in a blue moon I get a studder at idle for 15 seconds or so and then it just kind of clears up. He told me to clean the IAC valve. Right on top of the engine, 2 screws. Just unbolt the thing, take some brake clean and clean it out real well. Replace the gasket and stick it back on. I guess it just gets deposits in there and needs to be cleaned from time to time??? I'm going to give it a try. It's worth a $3.00 gasket. Just thought I would pass that on.

Clint

 

Hi Wildbird,I hope that work's for you,didn't in my case.Bought a brand(IAC) new one and it still has a dead miss when I'm at idle.Mechanic gave up and told me to take it to the dealer.Hesitate's on take off,stumble's at idle and usely get's so bad I think it's gonna cut off but catch's itself.Code's PO303 and PO404 missing on cyl.#3 and#4.The rough idle doesn't do it all the time but the miss is pretty regular.Seem's to run better on rainy day's?List of thing's Ive done are spark plugs,wires,coilpack,fuel filter,air filter,IAC.I've searched the archive's and have found numerous other people with the same problem but no one post the fix? 1997 F150 AT 4.2L w/ over 100,000mi.Anyone reading this and has the fix please let me know. 97fone50

 

I had the same problem with the '97 V6. Worse on hot days, better in winter. I had a local garage look at it several times and threw several hundred dollars at this problem without a cure. Finally took it to the dealer. Back in one day, less than 2 hundred dollars. It was one of the two o2 Sensors. Simple fix. I should have had the dealer look at it long ago.

 

Is there any way to check the O2 sensors? I know they are expensive, how much?? I have replaced the plugs9just regular motorcraft-not platinum) and the wires(autolite). Mine isn;t that bad yet. Just occasional rough idle, if I just let it sit in nuetral, it seems to clear itself out in 20 seconds or so. I guess the O2 sensor would affect gas miledge too? Thinking about replacing the engine when its time with an upgrade. Trashing the V6 and putting an 8 in her this time. Still cheaper than buying a new truck. Anyone know if a v8 mounts to the bellhousing on a V6 tranny. I DEF WILL NOT GO WITH THE 4.2 again!! Thanks for the responses.

Clint

 

Why trash the 6? It's problably something simple like the aforementioned O2 sensor that could unexpectedly go out on any engine, whether it be a 6 cyl or an 8 cyl.