Check for trouble codes of course. Sure, you could spend the money on a good Ford-specific EEC-IV diagnostic code reader, but why do that when you could just as easily test for trouble codes manually?

The Check Engine light may indicate a serious issue with your Cummins diesel engine. Here's how to check and clear the fault codes triggering that light.

Check for an additional fault code P0421 (catalytic converter efficiency below threshold). If you have a clogged catalytic converter the vehicle will be slow to accelerate and slow to build rpm.

Did you use an OBD2 scanner on your car to figure out why the check engine light is on, only to get the P0303 code? Here's what it means, plus possible fixes.

We show you how to manually test for trouble codes, perform a cylinder balance test or clear trouble codes on any Fuel Injected Fox-Body Mustang.