I have a 1997 F150 with a V-6 that has about 107,000 miles on it. Truck is in great shape and has never given me any real problems. For about the last month (since it has begun to get cold) when I first start the engine any time after it has had a chance to cool down it idles very rough. I park overnight in a heated garage and it still does the same thing so I really do not believe the actual temperature makes a difference. Once I run the engine long enough for the Temp guage to begin moving up it seems to run better.

I replaced plugs and plug wires at about 80K miles. I have checked and don't seem to have an issue there. I would appreciate any advice on what to check next.

 

Sounds like the IAC (idle air control) Theres tons of threads in here and easy ways to clean it. Same thing happened with mine, runs rough or sometimes wont even start for a few tries when cold, cleaned the iac which only took 30 mins or even less and problems gone. heres a how to thread.

http://www.fordf150.net/forums/viewt...er=asc&start=0

Just read the part about cleaning the iac. You should clean the throttle body if youve got a few hours on your hands but that should fix the problem. Should clean your MAF also, it helps alot. difference is night and day.

heres the MAF cleaning
http://www.fordf150.net/howto/clean-...low-sensor.php

And heres the handy full "how to's" articles
http://www.fordf150.net/howto/