I have a 93 F-150 with a 5.8 ltr engine. When in park it will idle at around 1800 rpm, in gear it idles around 1200 rpm. The truck runs great other than the high idle.
What is the most logical course of action? I was thinking of changing the throttle position sensor???
Thanks for any help provided!

 

TP sensor could be bad. You should read the value to see if it is within spec.

Idle speed motor also.