2003 Silverado 4.8L, it was stalling out and the lights dimming at idle, tested alternator came back bad so put a new one in it, this was 2 days ago. Now there is no rough idle, but when I am in drive and go to turn slowly, at idle, the truck stalls, no power loss at high speed or even when backing up. Anyone have any suggestions on what it could be?

 

Pull the intake tube off the throttle body and inspect for carbon build up around the edges of the plate. If it’s bad enough it can restrict air flow at idle and/or cause the plate to stick, so when a need for power is required (such as turning the wheel) the PCM can’t adjust the TB to compensate.

If it’s clean, there may be an ignition switch wire on the column that’s getting stretched/grounded when turning and causing an intermittent open.

Check for codes even if the light isn’t on - intermittent problems can often take several ignition cycles to trigger the light.

 

Ended up being a bad alternator from advanced, replace alternator truck runs fine.

 

never heard of an alternator causing stalling issues. maybe a poor connection on the battery or alternator that would only happen when turning. knew of another chevy truck that would stall when turning turned out to be a poor ground on the engine