You've got the opposite problem from me. I can't get reverse to let off.
. The easiest place to start is to have the pressures checked. After that, you will need a tech who knows these trannys. There is a clutch pack, a brake and a one way sprague that are used for reverse. I would caution you not to rev it too much or you will ruin the clutch pack. The scraping noise is probably the tips of your exhaust. The cruise problem needs to be described a bit more. Could be the amp or the actuator or the sensor..