my 2002 f150 idles at 2,500 plus, never goes down??

With high idle, I usually block off mouth of throttle body, it should kill the engine. If very little or no effect, you got false air getting in there ffrom somewhere? Clean the throttle bore and around throttle plate. Make sure throttle plate closes at idle. check and clean anything that has to do with idle air system. some ford have trouble with maf system, unplug the maf sensor, start it and drive, see if it does better? If so, have to check maf system. Any applicable trouble codes?

A stuck idle control valve is a possibility.

Thanks for answers everyone. No check engine light. gonna try with easiest checks first.

My trick is to remove one end of the hose that goes from the idle air control valve to the air intake and spray carburetor cleaner down the hose so it is sucked through the IAC. Once it idles down you can spray WD40 to lube the valve. If the valve is not too far gone you should see a big improvement provided this was the problem in the first place.

HI there. i coverd mouth of throttle body and engine stalls.I have no check engine light. I ended up replacing IAC valve but no improvement.still idles at 2.000 rpm and wont upshift when going down road in drive. Any thoughts? what is the maf system