i have a 97 blazer with the 4.3 v6 and im trying to figure out what is wrong with it. i was driving it the other day and it simply didn't want to move when at a light. it reved up then it engaged. it now only engages and moves if i let it sit for an hour but it only goes 20 or 30 ft then it just revs the motor. the motor still stars every time no problem.

 

Sounds like transmission is toast. But check trans fluid level and fill to confirm. Black burnt fluid is bad. Red fluid is good.

 

Check filter and fluid. sometimes a clogged filter will limit fluid flow and prevent the transmission from working. Although it sounds like the clutches are toast.

 

I would concur that the clutches could be bad. Do the easy checks first of course.

I was surprised how quickly my transmission went out when my clutches finally failed. It seemed like it was only over the length of a couple weeks that it came on.

 

I agree. The 4L60 doesn't "warn" you the same way the old Turbo 350 & 400 did. My 3/4 clutches failed on me with what I thought was little to no signs of impending failure. The signs are a lot more subtle with these 4 speed auto's.