Re: engine trouble
BlueBronco - You really need to figure out and be sure whether the tranny is slipping, or not. Since everything is OK when cold, you can do a simple comparison. When cold, from a standing stop (to be sure that trans starts out in first), tromp on it, and listen to the engine (watching tach is best if you have one), and see how far (distance) you go to get to 20 MPH or so, and how much the engine rev'ed to do this. I'm suggesting only 20 MPH because you want to stay in first gear to keep it simple, and use a good marker where you hit your speed.
Then repeat this, EXACTLY the same when it is well warmed up. If your trans is slipping, you should see and hear a lot higher RPM, and take a longer distance to get to 20 MPH or whatever speed you used when cold.
Be kind to Mom, but respectfully point out that there few vehicles safer for her son to be in, than a Full-sized Bronco!