How is the fluid level while in neutral? Make sure its correct, this trans can be tempermental with incorrect level. I would also drop the pan and change the filter again. Check for metal in the pan.
My 97' Grand transmission went out at 60K. The over drive unit is the part that usually fails (and it did) due to lack of oil to it(metal in the pan too). The oil passage is too small and needs to be drilled out to improve oil flow.
If it does need a rebuild have them install more clutch disc's in the over drive unit. Their are 2 clutch packs, one can take one more and the other 2-3 more.
If you want a transmission shift kit. I have a TransGo kit for the JGC auto trans. I bought it for a customer and did not use it. I put it in our JGC at overhaul... very nice shifting trans! Email me.
[FONT=Trebuchet MS]01' Jeep TJ (Jeep #5)
3.5 RE Custom SuperFlex, Raingler, Kilby, Currie, Banks, Borla, American Racing, Custom mods, Always more in the works.