Engine Performance problem
2003 Vauxhall Zafira Manual
approx 4 weeks ago car became lumpy when idle (as if misfiring) engine management light came on so took to local independent garage and they plugged into computer and told me it was air flow sensor which they changed but car was still running the same they told me could be ecu so they took to vauxhall and got ecu tested ecu came back fine. Since then the local garage has also changed coolant temp sensor, inlet manifold gasket, spark plugs and coil pack. They have also checked fuel pressure, cam timing and compressions. They have now given me car back yesterday and told me they dont know whats wrong with it any ideas?