Hey guys having another issue with the Ex. Over the past couple of weeks been having an intermittent problems after my truck starts up. The engine will crank and fire up w/o any problems but right after it will start chugging like it wants to stall out. It will do this for about 10 to 15 seconds then the engine will surge up till the rpms are about 1100 then settle back down to about 800 or so. She will run after this w/o any problems. Only seems to happen after sitting over night but it doesn't happen every morning.

I'm going to pick up a can of map sensor cleaner and see if that helps any. Maybe pull the IAC and try cleaning/replacing it. Any suggestions?

 

IAC sounds like to me.

 

I had an idle issue similar to yours when I had my '97 F-150 5.4L. Cleaned the IAC and everything went back to normal.

 

Could be a couple things.

As mentioned IAC, but also a leaky injector draining fuel pressure.

 

Moved to the 5.4L engine forum.

Stewart

 

Leaky fuel injector(s) causing the engine to run very rich until the excess fuel burns off.