CaptScott - You might try mining these sites.
http://www.boatsetup.com
http://forums.screamandfly.com
http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi
The "boat shaking fix" makes me think you might have a faulty check valve on your main fuel tank. You might have more than one problem.
When you run on a portable tank are you using the same fuel line/bulb?