4L60E won't upshift at the drags
 

My $l60E works great in drive,but when it hooks real hard at the track or on the street it wont come out of first until i lift,then it goes right to third. Also,after this happens, it has no first gear or overdrive until after i park it or shut it off,then everything works fine again,its a fairly fresh trans with an ATI ten inch converter And a 4.10 12 bolt.Other than that its bone stock. Would a fluid level be a possibility? It's dead in the middle of the level range.Please help I need to do some bracket racing.Thanks,Shaun

usually when they default to third it is because it has over heated.

Thanks, I appreciate it.