2000 Toyota Avalon Breaking system override

I have a 2000 Toyota Avalon I was driving to a store no more than 5 miles away from my home, and I noticed that my car just didn't feel right. The wheel was vibrating and I was not able to accelerate as I should have. I finally made it to the store and when I came back and started my car, my gear would not shift out of park. After about 15 minuets, I was able to move the gear to reverse and then was able to make my way home, but was not able to drive confidently because of so much resistance I couldn't drive past 20 miles pr/hr. I took my vehicle to my mechanic and he of course could not find anything wrong, and after a few days of driving, and not experiencing that vibration and grinding, I thought my car was ok. Now fast forward 3 months later. Within the last 3 weeks, my breaks system is over riding and my breaks are being applied as I am driving, causing me to have to constantly pull over and wait for the breaks to release in order to proceed driving. Why is the ABS doing this, how can I fix it, can I remove the ABS? 2 weeks ago as I was driving my car began to shake and the burnt smell of metal began, I took my car in for repairs and was after new rotors and break pads and large repair bill, I had hoped the car was ok. Then my mechanic did a test drive, and he experienced the same thing as was left on the side of the road while my break system released. He told me I needed to replace the whole ABS system. Could it be something as system sensors that need to be replaced?