I just bought a 1995 Chevy S-10 Blazer 4x4 (automatic) with the 4.3L V6 Vortec in it. I got it off of one of my friends for practically nothing. Anyway, when you start off it shifts fine from 1st gear to 2nd. When it attempts to shift from 2nd gear to 3rd, it acts like it's in neutral and the engine just revs. It continues to rev until your speed comes back down and then it shifts back into 2nd. I've noticed that the transmission is leaking oil around the main seal? (the pan that is removed when flushing the transmission). SORRY! I don't know much about this sort of thing. If anyone could give me any advice or tips I would greatly appreciate it. Thanks alot!

 

Welcome to the forum graylynx .
I had this problem once, it was a sticking valve body in the tranny, replaced it, been good ever since.

 

Check the trans fluid level and you might need to have a tranny shop do a diagnosis.