Greetings! New member seeking some ideas about an issue with my 1999 Grand Marquis GS. 82000 original miles and never been in an accident. I purchased the vehicle last October and live this car! In the past 3 months I’ve changed the oil and filters twice, serviced the transmission, rear differential, replaced the AC compressor, replaced the spark plugs/ignition coils and have a great mechanic that I trust. Now I’m noticing a slight “shudder” sometimes while accelerating up a hill and even when on the highway at high speeds. No issues with starting the engine and the idle sounds great. My thoughts are the issue might be fuel line related….but I know almost nothing about car mechanics. Any ideas would be appreciated! TY!

 

Any codes? A misfire that occurs long enough should set a code.

Next time it shudders, drop the gear shift out of over drive to see if the shudder disapears and post your finding..