Having just played Sherlock Holmes with my fuel system, I’m intrigued with your problem.
First, a few questions- Was the car running well 8 years ago? When you cleaned the fuel tank, did you find any sugar or other junk? Ethanol can decompose to sugar crystals. Did you test the spray pattern of the injectors before you originally cleaned them? If so, how did it look? Has the tamper-proof mixture screw been exposed? How about those 3 brass screws on the manifold? Are they seated as they should be?
Based on the length of time the car sat without being prepped for sitting and your symptoms, it sounds like the fuel system is fouled. I would look at the small things- the intake screen on the CPR, the little o-rings on the primary pressure regulator located on the fuel distributor, the fuel filter (you didn’t mention that at all).
One more thought- the lambda system is all about emissions via mixture control. Unplug the electrical connection to the frequency valve and to take it out- if the hardset mixtures are correct, you’d be able to run without it. If nothing changes, it’s not a part of the problem.