Djet running way too rich... Still! Options

[Halfnelson]

Had a previous thread starting in 2022 about my 73 1.7 standard D-Jet running way too rich and flooding to the point where it wouldn't start. It's been an ongoing issue. I've had a go. 2 garages have had a go. I'm at the point where I'm beginning to lose hope.

A recap. Bought the car 2021, had a problem with intermittent flooding. So far have:
Checked MPS - holding vacuum.
Replaced CHT sensor and tested. Working when flooded.
Replaced fuel pump and tested pressure.
Replaced all vacuum hoses and tested for leaks.
Valves set and rechecked.
New 123 distributor.
New injectors.

Each time I think I've cracked it and it runs and drives - sometimes for a month or so. Then I'll go to start it and it'll flood again to the point where it contaminates the oil. I feel like I've never managed to get to the bottom of the problem. Just keep replacing parts. Thinking maybe a return line that intermittently blocks? I'm kind of at a loss.

[JeffBowlsby]

While the idea of swapping in 'known good' parts like the ECU is noble, I have seen some 'known good' ECUs be functionally defective in some mode even though they seem to work OK. No harm in trying the swap as a first step as it may get one closer to any issue and solution. But that process is not definitive.

I have the equipment to test the ECUs, D-Jet or LJet, but I don't do repairs. Or send it to an ECU repair shop for their analysis and any needed repair. Verify functionality of every ECU function and take the guess work out of the equation.