94 Ford Aerostar van acting up after unrelated repairs... any ideas?

My hunk-o-crap had a wheel bearing replaced, the front brakes (apparently due to the wheel bearing), and a brake line (which just happened to break because it was rusted or something). My dad and his mechanic friend fixed it, and I picked it up this morning. While I was pulling out of the guy’s driveway, it stalled. It’s never done that. It nearly stalled again a couple of seconds later. When I got out to the highway, the speedometer needle was going crazy bouncing back and forth.. jumping as high as 70 when I know I was doing nowhere near that, maybe 40–50. The faster I went, the more crazy the needle was, until it was finally tapping the little plastic pin at the “fast” end of the meter… and I figure I was doing about 60–65 at best guess. When I slowed down, it was still showing me doing 15 or 20 when I was coming to a stop, so I obviously wasn’t going that fast, and it showed me doing 20 in the parking lot when I was just rolling.

On top of that, while I was on the highway (doing maybe 60–65 at best guess), it kept jerking the way a car does when it shifts. It wasn’t a hard jerk or a buck… it felt like a normal shift, only at the wrong time, and it did it more the faster I went.

I also had to stop kind of fast once, and it shuddered a little like it was threatening to stall. It did this maybe two other times as well while I was stopping at lights.

Does anyone have any idea? NONE of this happened before yesterday, but I’m pretty sure that a wheel bearing, brake line, and brakes aren’t related to any of the problems I’ve mentioned above.