[JCoop]

I assume you have 48 IDAs?

Popping usually means too rich; as opposed to sneezing, which would mean lean.

When this occured with my setup, I went lean on the idle jets (55s) and disconnected the distributor vacuum advance. Timed it to 38 deg. max and she's running great. Just a bit fat at idle but the transition is smooth and response immediate. You may want to go to the next smaller size idle jets, 60's maybe.

edit: This was on the GT40 w/ 302.