Odd transmission behavior...

[Fluxtasy]

I think with your high mileage, the transmission seals might have harden up or worn out.

I bought my car from the previous owner with 60k+ km and I doubt she has ever replaced the ATF fluid. It was stiff even shifting from N to D so at 65k I did a drain & fill with Torco ATF. It was a little smoother after this. This ATF has some additives to soften the seals. At 100k I replaced the ATF filter with fresh Torco ATF and after this it felt really smooth like new.

Please note that there are 2 Torco ATF fluids so you might want to check your owner's manual which is the right one. An alternative would be an additive like Lubegard.

If your seals are too worn then you might need to replace them instead.