Sounds like the vibration is REALLY excessive. First thing to look at is the prop. Important to balance it if you haven't. Most props are pretty close to good but I've had the occasional one that was way out of balance. Not sure how you would balance a spinner but that wuld be something to consider as well. Make sure all mount to firewall and motor mouunt bolts are secure. There are some pretty fancy mounts available (costly) but what I do is put a rubber washer that is about 1/8 " thick at each bolt between mount and firewall. FWIW