My new LT1 had a ruff idle with a surge. I found 2 problems. First, the passenger side breather hose had a crack on the under side at the throttle body where you could not see it. Replaced.
Second problem was with the pvc vacuum line where the rubber hose coming from the throttle body and connecting to the metal vacuum line was not connected.
fixed. Also I replaced the evap rubber hose at the throttle body because it was cracking. Idle very nice now. https://camaroforums.com/forum/membe...um-line-15719/
https://camaroforums.com/forum/membe...ure-map-15720/