f150 02', 4x4, auto, 5.4l, 125, 000 miles. I ran out of gas a little while ago and right before I cut her off she gave a heavy idle surge as I pulled into the gas station. It would go up to 1500 rpm and drop as low as 400rpm, the truck never fully gave out of gas, I cut it off as soon as I rolled into the gas station. Ever since it has surged at idle and will cut off if it sits under 1000rpm for more than a few seconds. I have changed the fuel filter, cleaned out the mass air flow, sea foamed the motor, and just recently changed the IAC. I thought for sure the IAC was the problem it was real nasty when I pulled it off. I bolted up the new piece and attached the battery with no luck. I'm at the end of my list of easy things to try. . . Next is the fuel pump unless there are any folks on here that have another idea.

 

If the IAC was really nasty, the throttle body probably is too. I'd pull it and clean it.

 

I agree with GLC but at the same time would have to add that running the fuel that low most likely clogged up the fuel filter as well. Good luck!!

 

Also do yourself a favor and do a fuel pressure test before you dive into the fuel pump.

 

Broken vacuum line, go figure. I have had a time with it and just over looked the small stuff. Found the broken line replaced it and idles like a champ. Thanks for the input fellas.

 

Yeppers. I need to check mine now. Yesterday my Idle acted funny and dropped to about 350 then back up. When the idle dropped that low it sounded almost like she was flooding. weird