The Mooney is actually a fine aircraft. But you have to fix it. The way it comes you have to constantly change the fuel tanks from right to left else you start going in circles. The way to fix this is to take this action: copy from the Cessna 172, the code "Cessna!Fuel_Selector" and paste it over "Mooney_Bravo!Fuel Selector" in the panel.cfg. The Cessna selector draws from both tanks at the same time keeping the weight distribution even in the wings. ;)
The Mooney is actually like that in real life so in reality there is nothing wrong with it. Although if you have a limited joystick, such as the one I have without all the extra buttons, it would make it easier to fly. I flew a 2000 Mooney M20S for my commercial and CFI certificates and every so often you would have to switch tanks to keep the proper fuel balance. Man that was a fun airplane to fly though. 8-)