My transmission went out and I had a used one put in, Here is my problem it keeps wanting to shift down and today on the freeway it went from OD to 3rd then after awhile the darn thing shifted down to 2nd at about 60 mph and of course my engine redlined and shifted back up after I let off the gas, but just to third, when this happens I have to run it up to 80 mph to get to OD and stay @ 70 mph to keep it in OD. Any Ideas would be greatfull. Second problem is my drivers front wheel is vibrating and today I pushed on it w/my foot and it moved back and forth like the luggs had been back off half way or the wheel bearing bolt was way loose. Any help here would be a life saver.
P.S. bolts are not loose. Im afraid the tire might just fall off.

Maybe your tie rods are shot or maybe even your ball joints. And when I mean shot I mean obliterated. Do you feel it on the steering wheel?