When the car reaches 45 MPH it seems to vibrate. Once I let off the gas, the vibration stops. Also, sometimes when I start it up, it starts up fine, but when I put it into reverse it stalls. I can then start it back up with no problem.
There are many things that can cause a vibration like what you are describing. Rotating parts that are off balance for some reason are usually the issue. Since a car has many rotating parts, it is usually best to seek help from a qualified technician such as one from YourMechanic to get a correct diagnosis on why your car is shaking. Tires that are out of balance or separated, driveshafts, u-joints, or broken carrier bearings can all cause situations similar to what you are describing. Driveline issues and separated tires can be dangerous, so I advise getting the vehicle looked at as soon as possible.
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