Weird issue after Jakes Performance build...

2001 Silverado 2wd with newer 4l80 swap.Did the swap and everything functioned as it should.Rebuilt same trans with the Jakes Performance kit and now I have a strange issue.On cold starts trans acts like it is "locked" up when you throw it in reverse it trys to go but feels just like the E brake is on,sluggish in forward gears as well.Fast forward to when it starts to warm up and the coolant temp hits about 136 and the issue completely disappears...I have spoken to Jake about it and he has tried to help,hes pretty sure its something in my tune but him being 2 thousand miles away and no tuners anywhere near me Im struggling to figure it out.Only does it cold and seems to away after it warms..Any advice is welcome I have zero experience with the trans settings in HP and have no idea if I need to bump up line pressure settings ect to fix the issue.:banghead:

Ran a scan today and found the 1-2 selenoid was on until it started to warm up and as soon as it went to off the trans went right into reverse like it should.Anyone know why it would be commanding that when the PRNDL says park?

Tried a stock tune ? that will eliminate 1 possibility.