1998 Shifting Hard

My transmission has ~90k miles on it. It shifts great when it is cool. But after driving for about 20-30 minutes it shifts hard, kinda making the car do a slight buck when shifting into 2nd and sometimes 3rd. I had the transmission flushed at my buddy's shop and it didnt help. Sometimes after long drives (over an hour), I can faintly smell hot tranny oil after the car is parked. I was thinking of installing an aftermarket tranny oil cooler. Do any of you think this would help?

Thanks in advance,
Steve

Sounds like my 98 (53000 miles),shifted great when cool and shifted hard when hot,ended up to be something in the trans being cracked and the forward clutch was being over pressured by a solenoid,the trans was chattering real bad on slight to heavy take off and at that point I had the trans rebuilt,hopefully thats not what you have,I would try the trans cooler it can't hurt,Good Luck

These cars have a problem with the torque convertor clutch, do a search and have your car's computer read at those speeds to determine if the TCC is activating (There is an overly simplified check you can do as well. It's outlines in the haynes manual: Tap the brake at 50mph very gently to see if there is a slight jerk, that will be the TCC disengaging properly)

I did the quick TCC check (at 50mph tap the brake) and I didnt feel any kind of jerk. Let me throw you guys some more info... After the car is warm, when shifting into any gear (the lower the gear the worse) instead of a single jerk when shifting it will kind of quickly studder in gear. Also, when slowing down to almost a complete stop and then taking off again the tranny takes a second to downshift, it doesnt downshift all the way when slowing down. I will try the oil cooler to see if that helps, but I'll be planning on getting a rebuilt transmission later this summer and swap it out (I have done engine and transmission swaps before).

Thanks for your time,
Steve