I just bought a used 2001 Blazer at99,400 miles. After 1,300 miles the transmission went out- had no reverse and from 1st -2nd RPMs went crazy as well as the speedometer...had a warranty got it replaced with a rebuilt. Within one day it is starting to do what it was doing beforethe trans went out, somewhat Here is what it does:
Whenaccelerating from 1st to 2nd RPMs go high(over 3)and it is a rough shift.If I go very slow it seems better. Now at 45-60mph it lunges in and out like I am taking my foot off the accerator..but am in cruise. Also at a dead stop RPM still is at .5. Check engine light came on 5miles after I got it back from the shop..they said they cleared it and check out all my codes.
Was my transmission the problem to begin with or is it the timing belt? Thanks for your advice. Am taking it back to the shop tomorrow. NOT HAPPY.

RJ

 

You have a timing chain not a timing belt.
Ask the shop to write down the codes that they get, then post them here so we can see what they are.

 

I'm betting that they didn't replace the torque converter... Sounds like a converter problem to me.