my blazer will drive but soon as it tries to shift loses all power if u turn it off then turn it back on it will engage again till it tries to shift any clues?

 

Are you saying that when you take off with gear selector in D or Over D, that it looses power when its time to shift from 1st to 2nd?

Or if you take off in 1st and then manually go to 2nd, do you lose power?

Trying to better understand your problem.

 

when i stick it in drive it runs through it till it tries to shift the loses power if u turn off truck start it back up it will do it again im not manually shifting dosent work either though

 

Is it neutraling on the 2-3 shift? Direct clutch failure is common.