94 350 TBI high idle

[RammerJammer96]

Just bought a 94 OBS with the 350TBI. There’s currently a spring to pull the throttle back closed to idle correctly and I don’t like it, so I removed the spring and I see why it’s there now. It will not idle back down after being revved up. If it push the throttle wide open it will idle at 3k rpm and stay there. With the truck off the throttle feels free and returns all the closed every time. Any idea of what could cause this? I have a spare tbi and I swapped the IAC today and it didn’t change anything.

 

[Schurkey]

First Guess: Worn throttle-shaft bushings in the casting. Usual fix is to remove the TPS, remove the throttle plates (no fun--gotta grind the screws because they're staked. They'll break the head off if the underside isn't ground away.) then remove the throttle shaft. Drill the casting and pound in bronze bushings, ream to size.

 

[evilunclegrimace]

Disconnect the throttle cable and see if the problem persists, also make sure that there is no binding or kinking in the routing of the throttle cable. Check to see if the TBI base gasket has failed and is contacting the throttle plates.