1996 Cadillac Deville No Throttle No Start
Sounds like the engine conrtol computer is messing with the engine. But if it is seeing bad signals from sensors, it may not be the computer. Hopefully the codes will lead you to the correct solution.
Suggested Repair
Have the OBD-II codes read with a scan tool and diagnose from those codes. The Service Emission Systems message means the computer has stored a fault. The loss of throttle response and no-start may be the engine control computer reacting to bad sensor signals rather than a failed computer itself.
Conversation Summary
A 1996 Cadillac Deville Concours with 140,000 miles suddenly lost throttle response on the interstate, then would not start. Oil service, fuel treatment, and new air and fuel filters allowed a brief normal start, but the pedal still did not work properly and the car failed to restart, showing Service Emission Systems. The expert advised reading the OBD-II codes, then researching and repairing the indicated fault, noting the computer may be limiting the engine because of bad sensor signals rather than being the root failure.
