CPS wiring problems.
My dad’s Wagoneer got so unreliable he was afraid to t drive it. It would randomly stall while driving. And finally, it got to where it would not start at all. At least then I could diagnose it.
We found that the Jeep often restarted by unplugging and replugging the CPS connector. But not always. We used the REM device to look for codes and got misled for a while chasing a fuel pump relay issue that was not real.
One day we were hooking up an oscilloscope to the CPS to see how the waveforms looked when suddenly the Jeep started up. We had suspected a problem with the CPS connector and the next step was going to be to eliminate the connector but somehow back probing the wires made the connection work again.
Careful inspection of the connector revealed that on one side of the connector the pins would push back as the connector was pushed together. By Back probing the connection, I had inadvertently pushed the pin into place.
I used a small pick to carefully reseat the pin in the connector and it seemed to stay put. Now where ever the connector is disconnected, I make sure that the pins are fully seated.
So far the random stalling has been eliminated. And the old Wagoneer starts up right away every time.