I don't think my gears are shifting, and my transmission fluid is fine, what else could it be.

Could be internal to the transmission like the torque convertor or one of your motor/trans mounts are broken. Have it looked at by a reputable mechanic.

Probably your trans, but try Lucas Xmission additive, sometimes it does miracles.Can't hurt. How long since you changed the fluid and filter?

I'm having same issue, 94 grand marquis ls, slips on occasion going 30 up to 40. Has to be first gear accelerating, going to try Lucas anti-slip today. Any thoughts on the front pump failing to create enough pressure? Fluid is still perfect full after flush and replace filter/fluid at 150ish thousand now at 161872.

My 1998 Grand Marquis slips when cold and sometimes hesitates on accelerating as fast as it should. I had fluid flushed at 83,000 miles with Merc 5 transmission fluid and now has 87,000 miles. I don't want to get rid of it, it's the rare park lane edition with the sunroof and not even at 100K miles.

Have the trans torque converter drained, the pan dropped, and new filter and fluid. Then add Best Line driveline additive, it frees valves that are stuck.

You have an email that I can message you at? I want to ask a few questions about this torque converter. The shop just dropped the pan and charged me 200$ bucks for the flush with new filter and the mentioned merc IV fluid

I'm afraid I'd get too many emails from other people. The converter has a drain plug behind a rubber cork at the bottom of the bell housing.(other cars don') It does need mercon fluid, but the converter holds more fluid than the trans, and it's important to drain it. Try the additive first (from Amazon). My Merc Van started shifting right after 12 years of not, just adding 1/4 bottle of Best Line.

OK thanks will definitely try it. Can't hurt to try after all I have 2 Grand marquis lol both very low miles.so I'll take the chance on this one.