my 81 does the same thing. it doesn't stall, but idle goes much lower than normal when i stop fast. i think its time to rebuilt her. it will studder if i rev it in nuetral every time, but only sometimes studders when in drive.
also, another sign that is telling me to get it rebuilt is on the first start in the morning, when the computer kicks in (which takes about 3-4 minutes) it will jump to about 1400 rpm until i tap the gas pedal. that might not be a problem, but i was just wondering if anyone knew what that was
thanks