Just replaced the valve cover gasket, throttle body gasket and spark plug wires and tried cleaning the IAC not my idle is at 2k... when i unplug the IAC it drops to 1.5k. Pretty bumbed after going through all that work so help would be appreciated, thanks its a 94 4.9 6L

 

Also replaced the fuel pressure regulator

 

Apparently cleaning the gunk out from around the throttle plates was a bad idea..? Who would of thought..

 

Any chance your throttle cable got messed with?

 

Checked that... its fine. Even with the throttle body off i cant really get it to close any more then in the picture...even with alot of force.

 

Anyone know if its possible to adjust how far the plates close on these throttle bodies?

 

Well, that wasnt the problem....tried checking for vacuum leaks but cant seem to find any... it now has a really high pitch like a vacuum leak but cant seem to locate where...

 

I cured mine by plugging the holes in the butterflies.

I did some trial and error by pulling the airbox hoses, starting the truck, and covering each hole with a piece of duct tape, one hole at a time. I ended up plugging both holes to get it to idle down. New IAC and TPS had zero effect on the high idle.

 

Are there any trouble codes?

 

What about your PCV valve, have you checked it? If it's bad or not a Motorcraft part it will definitely cause that. I had that issue.