I've had pretty much the exact same set of problems you are describing with an '89 SHO. After taking it to the dealer, it was found to be a camshaft position sensor that was in the process of going bad. It wasn't a cheap fix, but it did take care of my woes.

HTH.

Regards,


JaTo
Overland Park, KS
JaTo@kc.rr.com

99 Contour SVT
#143/2760
Modded to Taste

00 Corvette Coupe
Modded to Haste