1996 Chevy Lumina engine light keeps coming on

Theres a ton of things that can make an egr not fuction properly. Tps, map, vacuum, etc. Your engine should be pretty much mechanically sound before attempting to replace the egr valve. Try looking at your sensors and vacuum and see if something else is hindering the egr performance. Odds are the egr is fine, its just not being told the right things by all the sensors it requires in order to work right. You may want to check under the egr valve for carbon buildup as well. The chambers should be clear. There is an abundance of information on this at autozone and it is free to view. Do some research, im sure you'll find what ails you.