transmission or rubber-band
 

im having trouble with my 97 blazer 2wd transmission
while driving or from a stop, the rpms build past 2000 before it shifts and shifts hard like a jerk in the shifting.

Rubber band effect? I think you're going to have to elaborate on that to get some help.

the rpms build past 2000 before it shifts and shifts hard like a jerk in the shifting.

The SES light isn't on? I've heard something about the transmission going into a default "limp mode" where the fluid line pressure is at its maximum which would almost equate to feeling like a shift-kit.

When did this problem start, or has it always been that way?
Does this problem happen for every shift? 1st to 2nd? 2nd to 3rd? 3rd to 4th?

I can tell you right now that it probably should be shifting past 2000rpm anyway. If you recently purchased the vehicle it is possible that someone had some changes made to the shift points in the transmission. Otherwise it's possible they installed a shift-kit.