I've done the Flex Fuel sensor install using OS 12216125. After locating a 4l80e file that uses the same OS and performing a segment swap the trans would not downshift from third to first when coming to a stop. Hptuners support sent me a different file which solved the downshift problem but now the TC will not stay locked in 4th and when the shift selector is in D3 the PCM commands the TC to lock even thou in the tune it should not lock in third at all. In third when It locks It stays locked but in 4th it will constantly lock then unlock until I let off the gas to get below my targeted lockup speed. Hptuners support said that their segment swapper tool works as described so it has to be something on my end. Does anybody have any idea on what's going on or where should I start my search.