Has anyone noticed that the 4.2 seems to hunt for an idle when its below 50 degrees and the motor isnt quite all the way warmed up. When I crank it up on a cold morning and come to my first red light the revs keep raising and dropping. I thought maybe the IAC is getting a little stuck before it warms up (I know they tend to fail in cold weather). I dont think mine is bad though, only 39000 miles.

 

hi,my 4,2 idles spot-on and it is winter here in the uk with the temperature down to freezing. it may pay to check for vacuum leaks as the rubber 90 degree elbow on my trucks manifold had perished and gave similar idle problems.