Since no one replied to my thread question I can only assume that A: no one has had an EFI problem like this or B: they are just as baffled as I was. In the mean time I must have reprogrammed and tried a dozen chips with different setups. As I mentioned, in the beginning I had set it up to go into open loop idle at anything below 1100 RPM. I noticed, in the data stream, that the ECM was, in fact, NOT going into open loop idle so I set the closed loop enable to 235 degrees which forced OL all the time while reducing the max AFR vs temp scale to 15. No difference in the wanting to stall after deceleration (also DFCO disabled below 3000 RPM). The big tip off, as I said, was that this only happened while using the engine to decelerate the car and if just stabbing the clutch while letting off the gas it would drop to an instant stable idle. The difference here being that one way gives normal MAP for idle (about 17” of Hg) while the other way (using the engine for braking) jacks the vacuum like crazy. I noticed that the OL AFR vs MAP scale is somewhat linier virtually raising the “super high vacuum” AFR to almost 19 which most engines won’t run at. I cut this way down so any AFR reduction over normal idle MAP was flat. This worked like a charm and it now runs like a dream.
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