A friend of mine has a Starex A/T (ala 4D56 TDIC engine) whose auto tranny shifted only between 1st and 2nd gear (around 90Tkm on his odo when this problem happened) and wouldn't shift further. HARI casa wanted to overhaul his entire automatic transmission. He ended up going to a auto repair shop in QC referred by gray-market Starex dealers and the shop replaced an electronic chip called the "shift-position sensor" and that fixed the entire thing.

Could your problem be something of this nature?

You could ask around with those repair shops who specializes on the Starex since they are very familiar with the 4D56TDIC engine and I presume they have similar electronic controls with the original Mitsu 4D56TDIC engine.