[Formulajones]

All my auto transmissions that are controlled with a vacuum modulator do that when I'm up at high elevations. Low vacuum signal to the vacuum modulator will cause a delayed shift, most noticeable on the 2-3. As soon as I drive back down to sea level it's back to normal.

Not sure what elevation you're dealing with but it's something to look at. Could just be a simple adjustment on the vacuum modulator (screw inside vacuum nipple) If someone was messing with yours there is no telling what they might have set it at.

When I adjust mine down to shift normally at high elevation, it causes very quick short shifts when I'm at sea level, so it's a balancing act. I just have to live with it one way or the other or find a happy middle spot that's good enough.