car starts normal fine and then i take a drive somewhere and car will rev up on its own to 3k or even 4k rpm i can let off the gas and coast like im on cruise control if i want it to stop i rev it up a little and drops right back down to normal rpms
this has been really bugging me lately trying to figure it out car is a 87 rx7 t2

 

check throttle linkage,cruise linkage..any cables.
If that seems ok,you can disconnect the cables and see if the Throttle body 'hangs up' at a certain position.

 

you could also try lubing the butterfly and and linkages in the throttle body