Wife has a 1998 lanos, went dead. I have rplaced coil pack, spark plugs,sensor lead. Put it on diaognostics test and nothing came back, only to say timing cud be out. Got someone else to look at it who suggested tming fine but cub be egr valve, replaced that and flushed out and now petrol it starts but cuts out when i put my foot on accel. any suggestions