4L60E won't shift.
 

Hey guys Ive got a 95 formula. Its got a shift kit and stock converter. For some reason it will not shift out of first gear until i let off the throttle but only when i bring it above 3000 rpms. But it goes through all the other gears just fine. If its not a spendy fix thats good but this could also be a good excuse to do a t-56 swap. Any ideas what could be wrong with it would help.

Shifting is controlled by the PCM. It sounds like a very odd shift table in the tune.
Was the PCM or tune changed? Give us more history of recent changes to your car, especially what has been changed since it last worked. If this is a new car for you, get it tuned properly as it sounds like somone hacked the tune.

I just picked up the car for $900 non running. Turns out the whole motor had to be gone through and it ended up being around $3500. They never messed with the PCM or anything electrical. I pulled the motor, sent it in, then re intalled it just like it was before. It lasted for around 200 miles before it began doing this. Do you think if i got a tuner it would solve the problem?

I figured you might have just picked up the car in rough shape.
A bad MAF, TPS or MAP sensor might also give you those symptoms. A good scanner can verify that each sensor is sending valid data to the PCM. Once all sensors (also VSS) are verified, use a scanner to command each trans gear and verify that it shifts. This can be done with the rear wheels in the air and a good scanner, or have a trans shop do it for you. There is likely nothing wrong with your trans; just an engine sensor or the tune.
Sorry I cannot recommend a specific scanner for you because I, like many others here, use the very expensive HP Tuners or EFI Live which runs from a laptop.

I forgot to mention one piece of important info. I know its a new engine and all and i should get it broken in properly but there have been a couple occasions when i have put'er to the floor. At low speeds its fine, it spins a fair amount then launches. But at higher speeds (under 75mph) if i gun it it will rev way up like its dropping back to first gear or like the tranny is slipping somewhere. Since the tranny doesn't slip at lower speeds it makes me wounder why it would be doing it at higher speeds which then leads me to believe its dropping down to first gear while im doing 75mph.