I have a 95 C-280 with 168k miles onit and it runs rough. We have had the engine wiring harness, plugs and ignition wires and EGR valve all replaced just recently. The car still hesitates on occasion when accelerating, and sometimes backfires. The tech who worked on it also installed a mass airflow sensor, but this had no effect so it was removed. No codes show up at this time. Any suggestions? The car is in great shape and is worth keeping. Thanks