Compare your cal with the car's stock cal, see if any fuel/injector/closed loop/O2 control stuff isn't set properly. Commanded AFR/EQs, also.
I know your VE and MAF and Spark are probably gonna be different if you're done any CALC_MAF/VET stuff but I mean things like IFR, O2 switchpoints, etc. How's the fuel pressure?
Could be a leak of some sort, but the computer is pretty good at picking up that stuff up so it is probably in the tune.
something wasnt right with the IFR i think. i dont really know any of the details, but the guy who bought the car had it tuned, and it runs fine now.
I have a similar problem but it is only at idle. I am running open loop right now and at idle in gear it stays about 16.5 AFR, in park it goes to around 17.2-17.6 AFR. As soon as I give it any throttle at all it goes right to 14.6-14.8. When I go closed loop it idles right but pegs LTFT at 25%.