I have my truck on the factory tune right now. The air fuel is lean! Cruising around its 14.7 or so unless my t-stat changed the targeted air fuel. When I floor it from a dead stop the a/f will go to 14.5 to 14.2 up till 4 grand then go to 13.6 to 13.2 until 5 grand then it goes to 11.6. Lol. It will do this everytime. I quarter pedeled it out of a light. Enough for the torque convertor to stall up fully and go and the air fuel went to 13.6 and stayed untill it shifted to 2nd. I remember before headers with a muffler and cai my air fuel was 13.5 to 13.2. Trucks getting inspected tommorow had a check engine light problem. Can't wait to go back to a programmer. You can even smell the lean motor.