Cudadan.
If you have an front engine plate holding your motor in place, you might want to make sure the motor is aligned with the propeller shaft and rear in the right orientation. I think I might have the same issues also with this.

Make sure your front end is tight and aligned.

Make sure your rear springs have no broken leafs.

Check the rear spring center bolt that centers the leafs onto the rear housing

Check the front rear spring hangers and the front rear spring eye bushing for wear.