There have been several versions of the TF-2 kit over the years and there are a number of changes. Did you replace the 1-2 shift plug or grind the exisiting valve to get the shift on demand frature? I think that's what it was called. Basically if you did this mod, you can move the shift lever at any speed and the transmission will downshift. The original TF-2 kits you just changed the 1-2 shift plug that was included in the kit but the later ones, you had to grind your exisiting valve AND install a rectangular plate on to the bottom of the VB with some longer screws that were supplied. If you ground the valve but didn't install the plate, that could be the issue as well.