'73 2.0 D-Jet running way lean and hot Options

[scottthephotog]

So for the past 2 months, I've been trying to figure out why my '73 2.0L with stock EFI is running way lean and hot.

Backstory. I like gauges. I have the Dakota Digital cylinder head temp gauge and oil pressure and temperature gauges. My wife and I took it out to Santa Fe for the Route 66 meet. While we were out there, the MPS diaphragm blew on the interstate. When it blew, it began to run very lean and I didn't let the head temperatures get above 380F. We carefully slowed down rather quickly and pulled off onto the shoulder. Even at idle it was around 360-370F. We shut it off. We never lost oil pressure, but it got very close to the red zone on the oil temp gauge. Fortunately we were out there with @ClayPerrine and @Betty and their trailer.

As per my request, they made this wonderful emoji for me:
(IMG:style_emoticons/default/Trailer.jpg)

In the fall of 2019, the EFI wiring harness was replaced with a brand new one. All of the injectors were sent to Mr. Injector for flow testing and refurbishment.

We also have another '73 2.0L that is a restoration project. It is in lots of parts making it easy to borrow parts from for testing.

Since then here's what we've done:

1. Oil Change
2. Valve adjustment
3. Stole the MPS out of our other '73 2.0L until I repair the first one. (This one holds vacuum and still has the original seal that it has never been opened or adjusted.)
4. Confirmed the correct way the MPS plug goes with a multimeter and the ECU end of the wiring harness.
5. Confirmed timing was set correctly (27 @ 3500 RMP)
6. Confirmed the dwell angle was correct.
7. New points, rotor, cap, condenser.
8. Confirmed all of the injectors were firing.
9. Confirmed no vacuum leaks (and that vacuum lines were correctly routed).
10. Confirmed that all of the blades on the fan were intact.
11. Confirmed the air flaps in the tin were working correctly.
12. Confirmed the resistance of the head temp sender and ballast resistor.
13. Confirmed no blockages in engine tin.
14. Confirmed the MPS and ECU numbers matched and were correct for a '73 2.0L.
15. Confirmed fuel pressure was set correctly (29 PSI) and drove with a gauge to make sure it was consistent and there were no dropouts.
16. Confirmed the ECU was functioning properly with the factory ECU tester.
17. Stole the ECU from the other '73 2.0L, confirmed it was functioning correctly, and tested it it in the car.

The car has been on various test drives throughout this diagnostic process. In all of them, head temps cruising around town at 35-40 mph have been in the 340-350 range. This is about 50F hotter than it used to run. In addition, I have checked all of the spark plugs and they are bright white indicating a very lean mixture.


What am I missing? Clay and I have been trying to figure this out for almost 2 months now. At this point, I don't know what else to check.