why does my vehicle have an erratic idle it also flutters when driving unless under hard acceleration then runs great

any vacuum leaks?

Suspect EGR valve stuck open....pretty common problem back in the day.. Feel of EGR valve to see if it's really hot... If so its not closing! .. Another way to tell:: unplug one of the injectors on the TBI unit.. If idle smooths out.. Replace the EGR valve!!! .. Now, IF no luck with those test.. Possible failed TBI mounting gasket.. Have you had it scan tested?

CLEAN THROTTLE BODY AND SEE IF THAT HELPS