Check out my posts on my Star 22F here:
http://www.buggiesgonewild.com/star-...-legal-ga.html
This is a strong cart and has given me very few problems so far, and I'm not babying it at any time. Mine is wisper quiet and has no rattles.
The wobble you feel may simply be a tire that is "out of round." The cheapo stock tires on this cart often have one tire that has a flat spot. Watch them closely and see if you can notice the wobble on one of them. The real test is taking that wobbly tire and rotating it to another spot. If you notice the wobble on that new spot, it's surely the tire.
As for the unstability, the stock fiberglass roof and (steel? lead?) rack must weigh close to 100lbs. I've taken both of them off and replaced with a lighter rack for the top. This easy mod drastically changed thel center of gravity. Different wheels and tire combos can also give you a better footprint to ride on.
