more shifting questions

[1kwick6]

tranny has fresh rebuild less than two weeks old. 1-2 shifts awesome at 1/2 to 3/4 throttle;really barks the tires,2-3 shift is firmbut no tire barking; problem is when you go from a dead stop build it up just a little then go WOT 1-2 shift feels like a shutter shift , like a wheel hop but is happening inside trans. This ever happen to anyone else. any thoughts to what may be the problem?

 

[HOTTOGO]

Who rebuilt the trannie?

 

[1kwick6]

local tranny guru, has built many tr trans one is in a malibu running 6.50's