Grand marques is running rough on takeoff check engine light came on replace spark on 2 stop for little start back
Unless you just recently did a tune up never replace just one spark plug. Replace all 8. Especally if you have over 90,000 miles on the car and don't know when it was last tuned up. Most likely another plug has failed. What trouble code do you have now? HTH. -Jim
None now still running rough 180000 miles did tune up six month ago
It may need new coil on plugs (cop). Have the engine fault code read at a local parts store and post them here.
Looking for a Used Grand Marquis in your area?
CarGurus has 1,835 nationwide Grand Marquis listings starting at $2,000.
Search Mercury Grand Marquis Questions
Mercury Grand Marquis Experts