i have the 4.6 in my f150 and when its cold and the rpms are higher it really isnt rough. but when it warmes up and i come to a stop in gear it has a shake to it. when you even just touch the throttle it goes away. i was thinking maybe it was like an idle air control valve going bad but idk. other than this the truck has loads of power and runs great. anyone have any ideas what else this might be?

 

Check IAC valve for function.

Clean MAF sensor (search for how-to).

Check all vacuum hoses for leaks.

Any Codes?

 

no codes. i have took a glance at the hoses and they looked okay. i am prob gonna try looking at all the sensors this week sometime. how can i check the IAC for funtion?

 

Just check to see if it looks gummed up with any oil or varnish. I think some of them can be moved easily by hand.