1995 Monte Carlo, V6, Automatic, 100,000 miles. Shakes when Idling, or when maintaning constant speed, loses power/ shakes when excellerating but if I let off gas then reapply it smoothes out. I've noticed puffs of exhaust instead of constant flow. Problems amplified when it rains. Haven't stalled out so I'm not sure if its the IAC valve or not. When I press on gas to eccelerate quickly- very weak power at first then car jumps and revs much louder than should for speed.