Idle Problems when cold (below 40*) outside

On initial start up truck starts and becomes rough idle, almost stalls, clears up after couple minutes. After driving about 1/2 mile, stop vehicle, rough idle returns, then clears up for the rest of the day. Have already had coolant sensor checked, replaced coils, wires and plugs, replaced throttle body, checked fuel pump, replaced battery, idle switch. Has anyone else had similar problems???

Hey Propaneman
It would help if you could give us some particulars on the truck. Year,Model, engine size......ect. Just a question based on your user name, are you running it on propane?

Thanks for getting back to me........sorry for lack of details. I have a Ford F-150 Pick up, 2000......5.4 liter engine. I work in propane, but the truck is NOT fueled by propane. Any ideas appreciated. thanks

Hey propaneman
Been having computer problems, but got er going. Heres a few things to check. First check your vacumn lines, especially the pcv valve hose where it goes in the back of the manifold. Theres a molded rubber fitting that collapse`s and splits there allowing it to suck air. You can replace it, or fabricate one yourself. Check and clean the Maf , its located in the top of the filter housing in the tube. Check and clean the throttle body. And heres something that seems to give alot of trouble on these trucks, the IAC valve . This is probably your problem, but i would check the other stuff first. Your symptoms could be any of , or a combination of the above. I would double check the engine coolant temp sensor too, make sure youre not checking the temp gauge sending unit.

I agree with bubbles check all the items that he said. Always best to start with the easy and less costly things. I have seen several of these motors the 4.6 and 5.4 have trouble with the IAC valve. You can take it off and clean it with a tooth brush and throttlebody cleaner. I would recommend changing the gasket and not using the original. You will have to go to the dealer for the gasket but it is like $2.50 so no biggie... Good luck let us know if you get er goin....