How do I know if my Mitsubishi Challenger has a fuel blockage?

A fuel blockage is definitely one possibility. When was the last time the fuel filter was changed? But in the case of the earlier, petrol-powered Challenger, don’t disregard other things such as an ignition problem which could involve spark plugs, ignition leads or some component of the distributor or coil(s). Has the vehicle sat idle for any length of time? Modern fuel goes `off’ pretty quickly and poor or rough running is a classic symptom of that phenomenon.

If your car is the later diesel version, the same comments regarding the fuel filter apply, but the situation is magnified as the fuel systems on these modern, common-rail turbo-diesels are quite complex and run at enormous injection pressures. Sorting out a rough running problem in one of these Later Challengers is best done by first electronically scanning the vehicle to see if its on-board computer throws up any fault codes. Those messages can then be decoded and you’ll have a much better idea of what’s wrong. Frankly, the problem could be anything form a high-pressure pump failing to a throttle-position sensor sending false information back to the computer.