PhantomTA

Almost any kind of load below 2500 and the car breaks up, lots of popping in the exhaust and bad stumble. As soon as the car hits 2500-2600rpm it clears right up and runs great. Plugs and wires have been changed, 02 sensors changed. It does go a bit rich when this happens but I think its side effects of whats actually happening since I can pull fuel or add it and it doesnt change the problem.

Any ideas? I cant come up with anything... It all started with the cam swap (236/236, .602/.602)... I thought maybe something in the valvetrain was the problem, its been checked and rechecked and nothing is wrong.

Anyone?

ringram

usual story, someone hasn't dialed in idle airflow and part throttle fueling.
I think you need to get it logged. You might find timing, fueling and idle airflow are out.

Popping is usually retarded timing allowing unburnt fuel out the exhaust. Larger cams require more timing to combust the charge fully at low rpm as they are more inefficient there.