Finally got the appropriate fuel pressure fitting and tested the fuel pressure. It's solid at 35psi, but doesn't vary with engine vacuum. Tested vacuum and there's only 5-10 in.Hg. of vacuum at idle. That should be higher, and could be part of the whole problem.

Ugh, nevermind it all. Just did the exhaust pipe temp testing. 1-2-3 side is completely cold after running for a few minutes. Not just cooler or coolish -- room temperature.

Thanks for all the ideas, they helped.

So what does this mean exactly, that you are only running on 3 cylinders???

Yup. I added a bulkhead connector to simplify engine removal and the injector trigger wire for 1-2-3 wasn't secure and pulled out, so no fuel was being injected on 1-2-3. I'm now pulling all the pins out of that connector and making sure they're all 100% secure.

The 914 exhaust is separate plumbing for left bank and right bank. So the O2 sensor I added happened to be on the 'running' side, so it read realistic numbers, meanwhile the DME was on the 'dead' side and was adding extra fuel to compensate for the lean/non-running side.

But it's amazing how smooth a 3.2 will idle and even run with half the engine dead.

On the plus side, you're making progress. WILD though that it would idle well on only half. My brother's carbed 3.2 ran pretty rough with just one dead. I would think as long as you have the wide band sensor in stream with both you'd read off. My car just today with something as simple as the oil fill cap off was registering lean. I noticed it and started looking around and sure enough, cap was off DUH! Put the cap on and I was right back in the 14.4 to 14.7 range at idle.
Just read your comment again and noticed you must have a 2 in setup for the exhaust. That'll do it. But it's still really surprising you couldn't feel any difference in the way it was running. I noticed my car was a bit off with just the oil fill cap missing. It just didn't sound right at idle.