We're going to need the codes to help you. Read the thread below and post the codes here and we can help you more easily:Tony2u1951 said:My 94 SLS with 108K miles on it would not gain power this AM. I had just got on the interstate after filling up the tank. Prior to that it ran fine for 7 or 8 miles. As I tried to speed up I noticed that the engine seemed to be holding back and really straining to reach 55 - 60 MPH. Also, the service engine lite went on. It felt like it was in a lower gear, but the tach was registering 2800 RPM, so I think the tranny is ok. Any other thoughts.