700r4 issue 2-3 shift

[Wet..Paint]

When I first got my truck, It had a weak 305 in it and the trans was factory and felt like it was slipping into 3rd. After I put the new built 350 in it and I added a shift kit to hopefully help the trans. But now it seems like its missing the 3rd gear, then grabbing it. No idea how auto's work, but it feels like it shifts out of 2nd for a bit, then shifts into 3rd, and when it does grab it it grabs it hard. It doesn't feel like it slips at all, feels like it shifts out, motor revs up, then grabs 3rd.

I have researched it a bit but all I can find is slipping issues? What would this be? Should I rebuild it? Servo? Do I need to pull it apart to change the Servo? The most I ever did to a trans was, converters and shift kits..

Thanks in advance!

[beamn7]

Big thing is to make sure you didn't overtorque the valve body when putting it back in, got all the checkballs in the correct spot and the TV cable is adjusted properly. The 3-4 clutch is a common failure on the 700 (applied in 3rd and 4th gear), sounds as though it may be on it's way out OR the 3rd accumulator has a leak. Back side of the 2nd apply piston acts as the 3rd accumulator when 3rd gear is engaged.....
If it was me, I'd overhaul it just so I knew where I stood....

[Goldfinger]

Transmission fluid could be the answer the 700 is real nit-picky on this.

[1BadAction]

3-4 clutches on their way out would be my bet.