Transmission woes in Mexico

[makaira62]

I've got a 1985 500SEL automatic stuck in a little beach town in Mexico an hour north of Puerto Vallarta since October. The water pump and reservoir needed replacement; I was going back to the States and brought those parts back down to Mexico with me. The local mecanico put them in, all was well I thought, until I drove off the lot and the car would not shift out of first gear. Did a uturn back to the mecanico, but eventually got it to a local transmission mechanic. I ended up having friends from the States bring down a rebuilt body valve, modulator, and oil pan and seal, all recently installed. But now the car drives like a manual, having to shift to neutral before shifting back into drive, and not going further than second gear. Very weird. Acts better when it's cold, and gets hot within 20 minutes. The local tranny mecanico doesn't seem to be able to go any further with it. I'm thinking of paying a guy from Guadalajara to come out and take a look.....but does anyone have any ideas on what to check on next? It's got 134,000 miles on it, and I wasn't real good with maintenance, but the tranny oil seemed ok, not burnt. ANY help would be appreciated! Thank you!
Arlene, stuck in Mexico (better than CT though)