[6pack] popping/backfire at idle, low speed

[oliver]

72 tr6, triple carb, mild cam, electronic igniter, compression 10+, lightened
flywheel, polished/ported, decked, headers, etc

at idle, and low speed it pops/backfires at idle.

seems ok at higher rpm

doesn't seem to be moreso at deceleration

took all the deceleration bypass valves off and replaced gasket.  diaphrams
seemed ok, springs are there.

car recently had a full tune up etc and a several hundred mile trip on which
it ran ok.

thoughts/suggestions?