Lurching problem and I'm out of ideas.

Easy tests to do! I like you're thinking.

Disk front and drum rear.
I've inspected the brakes a few times in the last year but no luck finding the issue there. That said, I have to grease the backing plates on the rears so I'll take another look.
A warped rotor may not show up until it gets hot, you would also feel it in the brake pedal,

PS: We love pictures!!