My 97 blazer shifs unsmoothly

it sounds like you need a transmission rebuild

Check your transmission sensors with a network diagnostics. These are often to go bad, they also play a big role when it comes to shifting properly.

I had trouble with what seemed like a transmission on my ford van. Was told by a master mechanic to disconnect the NEGATIVE battery cable for 5 minutes to reset computer. I did this, it worked & never had another problem with it. Maybe it will work in your situation. Doesn't cost anything to try!:)

driving in 4wd on hard surfaces produces what is known as torque wind up as the wheels cannot slip so the variations of distance going around corners , dips in the road etc place considerable strain on the transmission , transfer case , drive lines and diffs
that is why it is difficult to get out of 4wd unless you drive with 2 wheels on a grass verge to relieve that torque wind up
as for the noise check wheel bearings and the cv ("U") joint at that wheel as there appears a proble where the dog teeth in the hub are not engaging properly or are jumping out of engagement

the trans receives a signal from a censer that tells it you have applied the break, which allows it to shift. do your break lights turn on when you push on the break?

your transmission has several electrical items in it from speed sensor to shif solonoids your car is getting hot because you are running high rpms you might want to pull some codes off your car with a diagnostic machine

I had a 2001 Chevy Blazer that would doing the same thing when the check engine light would be on. If you give it very little gas until it shifts into second, it does not shif as hard, right? Then you can accelerate as quickly as you want, but if you hammer it from a stop it jolts really hard.

Our local shop told us it was the valve body. They wanted $900 to fix it!!! They told us "Baby it all you what, but its only a matter of time. If you don't get it fixed soon, it will cause total transmission failure". We traded it in.

it could be your fuel regulator located on the top of the right side of the engine a c clip holds it on and it has an 1/8 line runing to the top it tends to set off alot of sensors its about 68 dollars

Check both O2 sensor(s) and catalytic coverter.. P0420 means catalyst below threshold. Also check the sensor at the transmission and solenoid.

YOU HAVE A SHIFT SOLENOID THAT HAS EITHER FAILED OR IS STUCK, DO YOU HAVE ANY TRANS TROUBLE CODES?