I have a 1999 4.6 and my truck randomly idles high. I had the codes read and have since replaced the air temperature sensor, but this has not compleley fixed the problem. Is this a common problem, or could it be something else?

 

You need to clean your throttle body. Sounds to me if its random that you might have some buildup on either the butterfly plate or the plate is hanging on the edges and cannot close properly.

 

I would akso look at cleaning your IAC as well. Idle Air Control. Although I guess this could vbe considered part of the throttle body.

Richard

 

Check your MAF sensor just inside the air cleaner. There are sprays made just for this so you don't touch it.

 

i would take the throttlebody completely off, be sure to get all new gaskets, and clean everything. pay some special attention to where the egr valve is connected to the base of the throttlebody. mine was almost completely clogged with carbon. had used like 2 cans of cleaner and a bore brush from my ar-15 rifle to get it clean enough. and as suggested above hit the other areas just as good.

 

My 04 lariat has idle problem high and low. At high fail safe mode comes on, when low shuts off , no warning or codes. I changed spark plugs, clean throttle body and maf sensor , changed oil. Man Whuts next. I love my truck so I needs to get her fixed any WISDOM on this issue