Hi guys...I run since new a 92 B-2200 with manual transmition. Lately when stop at a red ligth with the clutch on and the trans. in 1st. shift the idle goes up to 2000 rpm. The truck runs with the factory carb and it have never been rebuilt but all the vacum lines (excpt. the necessary ones), carbon canister and all those relays of the rigth fender have been removed and have a header instead of factory manifold.

Any info will be appreciated.

 

Check operation of both the clutch and neutral switches. Neutral switch is on rear area of trans with wire colors Blue w/ Green stripe and Black wire. Switch should change from open to close if gear shift is moved between Neutral and any gear. The clutch switch is the one that get depressed when clutch pedal is in released position, not the ones mounted down closer to the floor area. Wire colors to it same as neutral switch. Is a bit of a bugger to access due to location. This switch should change between open and closed depending up on pedal being engaged or released. Clutch switch very common problem so check it first.