Try disconnecting your high temperature cut out sensor. This is different from the temp sending unit. If you have the Chrysler engine it is located next to the temp sending unit. If the high temp cut out sensor is bad it will ground out at prematurely. On the Chrysler engines the sensor should ground out at 240F. You may want to verify temp with a infrared red surface thermometer to verify you do not have a cooling problem. If it is your oil pressure sensor beware there are two just like the cooling system. a sending unit that reads on the gauge and a low pressure sensor that simply grounds out. I can not see the oil pressure sensor preventing restart. chances are one of these is grounding out to force the shut down. Verify this by checking continuity through the sensor immediately after shut down. Hope this helps I have seen this before