4.6L plugs are black, runs rough with no acceleration on 1994 Mercury Grand Marquis

I changed the fuel Pump and got no good results.

by in Essex, MD on September 11, 2013
2 answers
ANSWER by on September 11, 2013
Have exhaust system and cat. converter checked for possible poor flow\partially plugged condition. This will cause backpressure and poor running. Is your check engine light on?
ANSWER by on September 12, 2013
scan codes and post so we can adv. also ck fuel pressure,it may be to high due to bad fuel pressure regulator