Revving high, brakes locked
 

I left my 2002 PT Cruiser at my parents so they could use for a few days (their car was in the shop).
I let them know to watch close it could overheat.
My mom drove it around town with no problems.
My brother went to drive it to work and it overheated (on the highway, no less).
They had it towed back home on a flatbed tow truck.
I came down to work on it to try and fix the overheating problem (see my other thread).
After installing several components, I went to drive it onto some ramps.
Once cranked it started revving like crazy! ZOOM, ZOOM, ZOOM up to like 3K rpm!
I hoped it would level out once I put it in gear. Once I dropped it into D it started leaping forward.
I put my foot on the brake to stop it but the brake only depressed like 1/2"! I had to put both
feet on the brake and press as hard as I could just to roll to a stop.
I went in and asked my dad about it and he confirmed the same thing as the only time he
drove it was a short distance after the tow truck dropped it off. He said he never needed to press the
gas and it quickly zoomed up to 45, and he couldn't press in the brake and had to use the parking brake to stop.

When I dropped it off, it had neither of these problems.

Could the tow truck have ruined something?
Are these problems fixable?

First thing to check would be broken motor mounts causing a hanging open throttle. As for the overheat, did you properly bleed the entrapped air in the cooling system before trying to drive it?

Good advice, I DO have broken motor mounts (they were already broke when we bought it from the only owner).
From more research, it looks like I could also have a vacuum tube unplugged somewhere?
The brake problem sounds like a brake booster fail or vacuum tube that has come off

Good advice, I will check that. The thermostat that WAS in there was failsafe and stuck open. The new one I put in was a normal one.