There was a DTB on the .3 trannys doing this. K2 accumulator spring kit. Available for about 5 bucks from Benz. Follow the instructions in the kit or if you can find them I'll fax you a blow up of the valvebody and the accumulators location. There also is a kit for 3-4 upshift.
However, its its been doing this for awhile, the clutch pack is probaly worn and the apply piston leaking as well whichh means overhaul time. Do yourself a favoe, KEEP the old spring and piston as you'll want them if you do overhaul it. I fought one for a couple days with a super hard 2-3 shift that turned out to have this kit in the valvebody. Once I reinstalled the old style spring and valve in K2 accumulator it shifted great.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.