There are a lot of variables here that you have given me. First, if there is a coolant leak, that should be addressed first to see if it eliminates the overheating. The t-stat could be fine as well as the radiator. Fix the leak first to see if that eliminates the problem before spending money where it may not be needed.
As far as the brakes, if the engine RPM's drop low enough, the vacuum assist to the brake booster will drop and can cause the brake pedal to feel hard to push. Is that what is happening? Also, have you checked to see if there is a vacuum leak that could cause lower vacuum and the vehicle to run poorly? When it feels like the vehicle is slowing quickly (when you let off the gas) are the RPM's high? I ask this because you mentioned it feels like it is stuck in one gear. Does it seem like any of the wheels are getting exceptionally hot (possible stuck brake caliper)?
One last question, has the check engine light come on? If so, have you had the computer scanned to determine the trouble codes?
Wednesday, April 23rd, 2014 AT 8:35 AM