hey mine did that too...although i have a 95 GST with a 90 4g63.
I did the following
bought new BISS with the O-ring(dealer)
bought new O2sensor (dealer)
checked all my vacum lines for leaks(none)
cleaned the Tbody till i could see myself.
adjusted the Idle speed like 1000 times
blocked the FIAV
changed the IAC on the tbody
and lastly i changed the MAF and that did it it quit stalling and the idle surge went bye bye..
good luck with yours man it took me like a month or so.
peace
isaias