07 chevy trailblazer 4.2 4l60e 4wd

Hi guys n gals ! I am gonna try to not make this
long and painful . Anyway I am trying to figure out
where else to go to on the trouble I am having. Yes
it sounds like a transmission issue but what if it
isn't.  So my vehicle is acting funny when it trying
to shift into 2nd. Doesnt feel like slippin as they
describe more like a hesitation when going into
2nd. The rpms rev up to almost 6 then u can force
it to shift or let off gas it usually does shift.  
So we have changed the :
  Shift solenoid a &b , down shift solenoid
Tcc (torque converter clutch) transmission cooler
lines,  filter fluid 3x or more. thinking about
changing the valve body but my partner is
changing the manifold pressure switch .
Any idea would be so hopeful nothing I have done
has fixed this issue. Thank u all in advamce