Hi mate just found your thread. Ive had/having a lot of trouble with my TB42 Auto box too; tps was actually missing from mine! It changed gears similar to yours. Having been driven so long (before i owned it) without a tps, the torque converter was fried. Been in and out of the workshop for a while.

Also: I think you should be driving with the OD button off unless coasting on the highway. I only have a POWER on/off switch but my mates has the OD button. He drives with OD off 3/4 of the time. But i think 60kph lockout is a bit low

I have a haynes book and it tells you how to do the auto box's self-diagnosis. Handy if you can get hold of one.

Goodluck mate