95 tahoe not shifting properly

[mwarner619]

I have a 95 chevy tahoe and recently had some work done on to get it running again after it died on me, but for some reason when I got it going the transmission stopped working right. It has a hard time shifting into 3rd a nd then it wont shift into 4th, could this possibly be a vacuum hose or something similiar and if so where could I find it because im lost

[maxwedge]

The shifting is done by the pcm from various inputs from specified sensors, make sure the main plug on the trans is securely in place, for starters.