My 98 V6 auto tranny shifts good 1st through 3rd but when warn, really slambs when going into OD. Fluid level is good and oil is clean. Filter changed at 60,000. Now has 91,000. Any suggestions?

sounds like the 3-4 accumulator is shot.

Is that an internal component? Does that mean major trans overhaul?

Access to the 3-4 accumulator is relatively simple, it won't require tranny overhaul. If you feel competent to do it yourself, it's mounted on the side of the valve body, it'll be a cylinder-like shape piece attached to the valve body, remove the attaching screws replace the piston and return springs, reattach and go from there.

Thanks. I try that.