ok heres the deal... I have a 91' Trans Am LB9, 700r4 w/ about 136,000mi. It has alot of milage so the tranny could just be on its last leg but I just wanted to see what could be going wrong.
I was driving home last night and car was fine. After one light It was in drive and it shifted from 1st... to 2nd..then when its supposed to shift to 3rd, it seems to downshift and rev to a high rpms and start pulling pretty hard. When i let off the gas its like nothing happens and it just goes back to around 1,000rpm like it usually does with no throttle. I can manually shift to second from 1st but when I put it in 3rd it seems to slip a bit then start pulling at a higher rpms and it wont shift to a higher gear. Can anyone tell me what they think could be going on? Any input would be helpful..thanks

 

3rd is the usual failure in a 700. As the trans wears, it slowly looses pressure. At some point, it gets low enough for third to slip. Also some of the valving will start sticking which will also lower the pressure.
It won't shift to 4th because your on the thottle but not going fast enough for 4th.
Keep doing that, and you'll completely burn 3rd. I've had 5 700's apart, all had 3rd burnt.
Plan on a rebuild, soon.

 

Yeai figured as much. Guess its time to take her off the road, was planning to do a 350 swap soon anyway.