[chiphead]

Any idea of any modifications? Its possible a shift kit disabled the detent valve. You don't absolutely need it if you have a good ratchet shifter, and/or you're racing it and dont want it to affect shift behavior.

It should delay upshifts and force downshifts when pulled. Its also possible the governor thinks the road speed is too high to downshift, but you would typically see it shifting too early under normal operation. If you're happy with the part throttle shift points and shift feel, check the governor and VB for a shift kit, but make small changes so you don't upset the apple cart.