When I first start my 89 5.0 in the morning the rpm's shoot to 2500. When I push the clutch in to shift the engine rpms go to 2500 as well. It doesn't do this all the time about every other day or so? 2500 rev equals gas waste!!! please help!!!

 

run a koer test and look for codes if none exist clean and or replace IAC and make sure throttle cable is not binding and that the throttle body flap is clean and free of carbon build up