Any idea on this stalling problem with a twist on a 1990 300TE guys….

The problem appears to happen after the car has been running for 20 minutes and some times soon after when the car has been switched off and on again. The engine will tick over normally until the car is moved ,it will even stall if the car is in neutral and pushed a few feet backwards or forwards.

I have already replaced the following items already:

1.OVP
2.ECU Temp Sensor


Any help gratefully received