1993 Cadillac Deville slipping

Could be an indication of an internal trans problem. Check the fluid level and condition. Is the color pink, or brown, and does it have a burnt odor to it?

Lets get a little more specific with the problem, so we are on the same page. A slip in my opinion, is a sudden raise in rpm, without forward movement. When does this occur, from a standing stop, during an accelerated upshift? Does it do this all the time, under the same conditions? How many miles are on the vehicle? What has been done to address it, and how long has it been happening.