The reason I'm questioning the WBO2 sensor is the engine sounds happier until the handheld AFR changes from WARMUP to a number and then it starts to sound worse. Plus the AFR numbers are always way too low. A buddy said to try the propane gas trick to find a vacuum leak. I'll try that and see if I can find one. I found it interesting that the MAP readings were below 20 inHg for a good portion of the first startup in the video below after checking vacuum at 2500 RPM. I did try another time with the Atomic EFI set to mild cam and it idled better, but the AFR was always off target. Target is 14.0 idle, 14.7 cruise & 12.8 WOT.