Code 55, Pcm Error
WARNING: This page is about a different car, the 1994 Cadillac Fleetwood. However, it is still accessible from the selected car via links, so may be relevant.
Ensure PCM grounds are okay. Ensure correct EPROM is being used and that it is properly installed. If okay, replace PCM. Clear codes, confirm closed loop operation and check operation of Malfunction Indicator Light (MIL).