For the last two years, my "88 Formula has been acting peculiar. At a steady highway speed it would suddenly lose power but if I got into the throttle it would recover. This would not happen every day. The last time I took it out, the car died completely and refused to start unless the gas pedal was on the floor, then it would start and idle at about 2K rpm but would accept any load. I nursed it back home with a feather light touch on the gas. I suspected the TPS, so I swapped it out from my '85. It now start and runs, but runs rough. Has anyone else encountered this problem ?
The fuel filter is about a year old. Upon further examination, I found that the car runs OK until it reaches operating temp, then it stumbles and will not accept any power. The Check engine light comes on, but when I query the ECM through the ADL no code shows, not even the initial code 12. I am beginning to suspect the ECM itself. When I let the car cool down, it will start and run OK until the temp comes back to normal, then it starts acting up again with the same symptoms.
Have you logged the ECM data stream? I'm having similar issues and discovered the the coolant temp sensor input dropped big time (200F to 30 F) from one moment to the other, causing the engine to stumble and hesitate under acceleration.
