Look up temperature sending sensor that’s how I found it. So that’s what I call it.
More accurately, temperature sending unit for an instrument cluster temp gauge. Vehicles with just a "HOT" light would have a temperature
switch.
"Sensors" are generally regarded as being for the computer, not the instrument cluster.
Also I pinched the return line off going back to the fuel pump to see if the the pressure raised when the fuel pump is initiated. And I didn’t see the psi rise at all. So I’m thinking a new fuel pump is a must.
Verify that the pump is getting proper power and ground by testing for voltage as close to the pump as practical--generally at the harness connector just before the harness goes up 'n' over the tank, and also check for voltage on the ground wire.
I'm still suspicious of the accuracy of the gauge you're using for fuel pressure.
I’m no genius but if the fuel pressure is that low it would be lean not rich. But again this computer has tricked me once before on these trucks.
Misfire causes the O2 sensor to report false "lean" signal to the computer. This puts the computer into Rich Command, trying to raise the voltage of the O2 sensor.
But you don't have an O2 sensor yet, so the computer cannot get to closed-loop operation. It's bound to run a little rich.
Find the cranking compression pressure of all eight cylinders.
Is the spark powerful enough to RELIABLY fire across the gap of a spark tester calibrated for HEI?
Any chance the spark plugs have fouled?