Tranny Slips and ideas?

92 Passat GL automatic slips when cold buy when warmed up it is fine. Any ideas. Thank you for your time. Ever heard of this?

My 91 passat auto slips in second gear , mostly when warm , for over a year now , but just recently its shifting harder and more positivly , and not slipping at all . could this be an electrical problem that some how fixed its self (maybe a bump ? )