Mike Butterfield

Can any one enlighten me as to why my 89 XT6 2X4 flares into high gear? It also has what I'm told is morning sickness, where it won't move for 3-4 seconds after setting for a couple of hours. I spent a thousand dollars on a rebuild and it still does the same thing it did before I threw all that money at it. The rebuilder is blaming the car. Could it be the computer? Is there any way to disable or go around the black box? I would not have a problem with flipping a switch to lock up the convertor and eliminating the magic in the box. I love the car except that every time it shifts into high, I just grind my teeth, cause it just can't be right what is happening here. Thanks in advance for any help or advise.mb