2001 Audi A6 2.5 TDI Tiptronic transmission problems

Hi! I have a 2001 Audi A6 2.5 TDI with tiptronic transmission. It has a weird problem. Sometimes it works normally but sometimes after a braking for example when I get a red light it twiches and the engine RPM goes up to 1100 (normally when I stop with the car its about 800). When this twich happenes, then the shifting goes crazy. It forgets to shift up in D mode but if I put it in tiptronic then it shifts. It makes big twiches when I put in R or D. After an engine restart the problem disappears for a time and then it comes again. We don't get any error codes from transmission or engine. (We got only an error in the comfort unit which was an engine communication failure or something like that) The transmission was just partly rebuilt and cleaned and got new transmission fluid too after a 17114 transmission error code. Before the 17114 error the car made the same problems like now, but when it shifts, then it shifts that smooth like never before, so I don't understand what's the problem. In the service they cant tell me too. Any ideas?