Welcome Mike,

I had a similar problem with my 84, it had sat idle for a couple of years but the tranny had been serviced before it was parked. A post here mentioned that many trans problems were really due to a poor running motor. Cleaned out the boost line to the alda, adjusted the bowden cable. Lubed all the throttle lingage joints. Excercised the modulator with a Mityvac. Replaced air and fuel filters. Cleared it all up.

Good Luck
Jerry