I have a '98 STS I have owned since new and it has been a very good Cadillac. It has 92k miles on it and just today it started up shifting very roughly with clunks and noises and the transmission light came on. I parked it and when I restarted it, it drove fine and the light went off. Any ideas on what could be happening? A friend said to look at the transmission servo. Since it set the Trans. light off maybe there is a code stored? Any advice would be great. Thank you!