I have a 2000 F150 Harley. My truck is trying to idle at about 400rpm and wants to stall most of the time when at idle. Other than at idle, it runs fine. Before now, if I could get the truck to hold and idle and open the hood, there are two vacuum lines that run into the main intake that runs to the air filter. If I take the top one off (when running) and put my finger over the line it stalls the engine...when I start it back up the truck runs fine and at normal rpm. Now, that does not even work. When cold, the rpms surge and the truck will not idle without stalling (I temporarily adjusted the idle for a quick fix). When warm, the rpms are too low to keep the engine on.

Any ideas on this? Sounds like a vacuum issue to me, but that is my weak point.

 

i assume you have a 5.4?? how did you adjust the idle?? check your I.A.C valve its probably dirty. also check your air filter is it dirty??

 

Yes, sorry...5.4


All I have done thus far is change the air filter (long overdue anyway), the pcv valve, check the coil packs and listened for leaks in the vacuum system.

 

Well, with no real way as far as an adjustment screw, I placed a nut on the end of the throttle adjustment

 

I got this pic off another post, but would this be the IAC valve? Where the white arrow is pointing?

 

its directly behind the throttle body. small round cylinder looking thing. its just to the left of the arrow.

 

Like I said, got this pic from another post, but boy...that looks like a fire waiting to happen! Thanks for your reply. I will go check and see if this looks dirty.

 

you will see a needle looking thing inside. it will probabpy be full of carbon etc... that needle has to move back and forth its probably stuck. take some carb cleaner spray it out, a old toothbrush work well to get in there to scrub all the crap off it, or a q tip works as well.