Hi Toyanon, it sounds like you know your stuff. Welcome to newhilux crew, it's always good to have some expertise here to help others.
Hazzy I would have gone that way too, rear brake shoe dragging, they tend to release when moving forward. If you leave your Hilux for long periods, I would leave the handbrake off and transmission in park. That's what I do and it hasn't locked brakes ever. I leave mine parked for a couple of months at a time and no problems
The other possibility that happens to mine, if the vehicle has been standing for a long while, the fluid in the transmission drains from the galleries and torque converter so it takes a while for the fluid to fill again, making the vehicle sluggish to move either direction. Just needs a little extra revs to get things flowing again
Cheers Gipsy
although I'm sure somebody will challenge that
even Einstein wasn't certain of his theories.
My 2013 auto D4D DC SR5, prefilter, 3" exhaust and Chip with egt probe, stock SR5 rims with Toyo Open Country AT2 265/65R/17's