A4Audi-96

I have a persistant transmission short (I think)that affectes the gear selection on a 96 a4 2.8 with auto trans.

I had the multifunction switch replaced about 6 months ago after car would not start, a few months later it started to miss the gear selected as I shifted, or not find gear at all, then when selecting reverse it would kick into limp mode, stange thing is it would work fine after the car was fully warmed up, all gear ranges, no problem till it cooled again...

I tried to clean the harness that runs along the bottom of the trans, no real change, except now it does not go into rev at all,

Once it is in limp mode it drives and shifts fine, (except no top gear as designed)

Thanks for any assistance or if you could recommend another source for advise