1977 Chevy Suburban

1979 Camaro engine with 30,000 miles in 1977 5/29/08 Suburban stalls when put in drive. Sometimes backfires through carb. New plugs, rotor, cap, wires, exhaust pipes & mufflers, oil & filter, air filter, fuel & filter, battery, radiator & coolant, vacuum hoses. Carb repaired, rebuilt, float set by expert - not perfectly retuned yet once installed. Warm idle speed = 850 rpm. Timing about 6 BTDC. Haven't checked dwell. Fuel pump appears to work well. Engine purrs. Tranny oil, fllter, & kick down cable replaced, works well. Other non-engine repairs done to make it run like new.
Previous engine came to abrupt stop when cam shaft disintegrated cue to teen racing engine. Wondering about torque converter. Drives well if I goose it after putting into drive. Haven't driven more than 300 feet - afraid to break down beyond pushing distance.
6/2/08 Found vacuum line not connected and fixed that but still stalls when put into drive and when going slowly enough. Stays running a bit better though.
Choke is opening when warmed up.
Sprayed carb cleaner around carb while running but nothing changes.
6/7/08 Wondering about torque converter. Haven't found anything needing fixing yet.