FiTech EFI system
I've tried the same. I'd prefer not to have to set the accel pump setting that high too, because I get the same thing. It goes pig rich.
I began reading through the definitions some more.
Under PRO TUNING, and then under 6. REV LIMIT DECEL CUT, there are values labelled Dfco. These are Decel Fuel Cut Off. Basically, when the throttle is closed or closing it will turn off the fuel below a certain MAP value, and then add the fuel back once above it again.
My default settings for cut map (03) is 28.00, and the return value (04) is 30.00
Looking at some logs, my car is cruising at 26-35 depending on the grade of the road with the TPS between 5 and 12. When my TPS drops below 5, my MAP value will drop to 12-22.
So what I'm going to do is set my cut MAP (03) to 19 or 20, and the return value (04) to 22 and see if that helps.
The Dfco Return Fuel (05) is the amount of fuel it adds back when the MAP reaches the trigger point (30 default, and I'll be setting it to 22). This should be tuned so that when you go from very low or closed throttle (Coast) to slightly open, the AFR shouldn't go rich, but should return to a normal range rapidly.
Probably take me a few days to get some miles on it to test this theory, but looking at the logs I'd bet that's what's happening.