I have an 85 Z28 with a 305 TPI and 700r4. I took the car for its first real drive yesterday (just got it a week ago) and it shifted fine accept for not going into OD on the Hwy (was cruising at 70 at 2500 RPMs) and when I would stomp on it from a stop it wouldn't shift until i let out of it. This morning when i was driving, it wouldn't shift out of first, and if i let off of the throttle and then give it throttle again it would free rev until about 3000-3500 RPMs and then it would catch. But if i put it into neutral and back into drive it would catch right away. I pulled over and shut the car down and let it sit for a little bit and fired it back up and started driving it really easy and it seemed to shift fine. I have checked the trans fluid and its full and isn't burnt, and i guess my trans doesnt have a modulator valve. I am completely lost and I'm in need of serious help!!

 

The 1982 - early 1987 units were bad for having sticky Throttle Valves. This can cause the intermittent shifting problems. The TransGo Senior Shift kit will fix this and much more. I have the modified version of these.