94 Jetta transmission problems after engine swap

After the shop I bought the Jetta from replaced the engine on the Jetta ( I test drove it before engine swap and tranny was working ok ) with a 2,0l from a 97 model, the transmission will only shift in D from 2nd to 3rd gear, you can shift it up manually 1 - 3 , OD will NOT engage, reverse works fine, tranny has new fluids and level is ok, motor check light comes on occasionally at different times, but motor runs excellent !

Someone told me it might be due to mismatched tranny codes, computer needs to be reset ??? Anyone who can point me in the right direction since the local VW dealers and tranny shops are CLUELESS !

Thanks

If they only changed the engine I doubt they changed the ECM so there should not be any mismatch. It sounds like the trans is in limp mode, have the codes read.