LQ4BU

If I'm driving along around 35, floor the gas, it kicks down as it should to 1st gear, then shifts to 2nd, then 3rd. But during that kickdown, while in 1st gear, it feels as if it slips somewhat, because when it shifts to 2nd, the car pulls much more than it did in 1st gear. At the track though, launching from a standstill, it feels fine as it goes through 1st, even pulls the tire a few inches. Trans is a TH350.

Anyone ever seen this condition before?