I been running a canned mail order tune on one of my import for about 6 month. I decided to go ahead and sell the vehicle so i returned everything back to stock. Stock intake, stock tune and stock exhaust, but when i returned everything back to stock my cel came on for lean condition. I did some datalogging and my LT fuel trim is at close to 35. I checked and checked for any leaks or problems but couldn't find any. I dont get it, everything was fine before i returned everything back to stock. Does anyone know what might be the problem?