put 727 together. slips 2-3

Sounds like something is wrong with the band apply like out of adjustment or maybe the anchor or servo strut.
TF transmissions will skip second all together if the band doesn't apply.
When I first got my car and drove it home it jumped straight from 1-3 because the band was so far out of adjustment the servo pin never clamped the band, so it just skipped second all together.