2001 Ford Windstar Misfire and Unstable RPM - Diagnosis and Fix

My 2001 Ford Windstar is experiencing a persistent misfire, causing the engine to struggle to start and maintain stable operation. I have to continuously press the throttle pedal to get the engine running, and once it starts, the RPM remains unstable. This makes driving extremely difficult and unsafe. What could be causing this issue? Is there a specific diagnostic step or repair that can resolve the misfire in a 2001 Ford Windstar? Any insights on how to fix this would be greatly appreciated.