Just installed my built trans for my lsx s10 blazer a few days ago, along with a 2500 stall converter. I'm still breaking it in but noticing the trans is very inconsistent. I'm trying to decide if a tune will most likely take care of my issues or not. I've never drove a vehicle with stall and i have no idea why sometimes from a stop it will stall out to 2500 and sometimes it wont stall at all and take off like a normal car. Its completely random...

I have almost 300 miles on it and i thought i'd try and see if it will down shift from 2nd to 1st but all it did was sit at 3k rpm and and fall on its face... driving 65 I gave it 50% throttle and dropped to 3rd perfect and pulled hard.

Just looking for some insight.
-2wd 60e
-2500 stall
-running ams oil atf
-rebuilt front to back with new 13vane pump, high energy clutches, steels, band, new transgo separator plate, transgo hd2-c, billet servos, other valve body mods, new beast sunshell , reverse drum, 29 element sprag. list goes on.. Its not super crazy but supposed to be enough for my 6.0 s10 blazer. Thanks for the help in advance.