95 chev Lumina w/170k. Took it to my mechanic and he put it on the computer and it indicated the EGR valve is bad. My check engine light would come on like once every few weeks and stay on for a couple minutes. So, I purchased the 160.00 EGR valvge and installed it, but my check engine light is still acting the same. Engine is running smooth and quiet. Idle is smooth as well. Any other ideas what it could be? Could it still be exhaust related but something else? O2 sensor? I will have it diagnosed, but wondered if any of you experienced this same issue. Thank you all. Really value any insight here.