If the EGR was not functioning you should get a CEL. You can check the function of the EGR through various tests depending on which part you suspect is going bad. The FSM has these procedures outlined.200sx98fl said:Okay my mind has been exploding on why my car is having a rough idle..and now some times hesitant when i jump on the peddle. I baby the shit out of this car with regular maintence and i dont know why shes giving me a hard time... Now the other day i checked my timing and somehow i was advance to the last marker..i think 20..(dont know how) So i retarded the timing to like 13. Adjusted the idle while i was at it. Rechecked and still had the problem. Now im messing with the egr system and when i pushed up on the egr valve the car almost died but it didnt it. It acted like it was going to stall but never did. Is that right? Would a leak in the egr tube (from header to egr valve) cuase this? Im going out today and recheck the gaps in my spark plugs...check all vacuum hoses..clean the iacv and tb. Please any help??