I have a '97 Deville,N*with 70,000 miles. During acceleration from a stop the transmission seems to be slipping briefly and then reengaging. This problem is worse if you begin to accelerate and then let off the gas and then resume acceleration. Local dealer road tested it with a scan tool but was unable to come up with any fault codes. His solution was to put in a rebuilt trans-misssion for $4000 (not happening).My solution was to have him change the fluid. The problem still exists. Any Ideas?