My '92 VG started running rough at lower speeds. Ran good at highway speeds. Got worse to the point that it shook bad when idling. My first thought was bad fuel injector, but all are good. Replaced plugs, wires, distributor cap, rotor, ignition coil, fuel filter, pcv valve and even replaced the distributor itself. It's not giving any diagnostic codes. But, before it started running real rough, it seemed like it was using quite a bit more gas than usual.

Any ideas would be greatly appreciated. I'm at a loss and don't know what to do next.

Thanks

Edit:
Forgot to mention that the air filter was also replaced. Car ran the same before and after all new parts.

 

have you done the diagnostic for the o2 yet?

 

No, I remember reading a procedure to check the o2 somewhere, but can't seem to find it again. Would the o2 cause the type of problem that is described?

 

Yes, among other things.