Perform Road Test
WARNING: This page is about a different car, the 1995 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Ensure engine is warmed to normal operation temperature. Start engine and allow to idle for at least 60 seconds. Drive vehicle with engine speed at 1800-3200 RPM for at least 5 seconds. Return engine to idle for at least 10 seconds. Repeat procedure 10 times or more. If MIL/CHECK ENGINE light stays on, replace PCM. If MIL/CHECK ENGINE light goes off, check for intermittent fuel injector leak. If injectors are okay, replace PCM.