Wow,
I was just thinking of starting a thread about this topic. I've been doing this for 23 years and have burned out twice. Just about every racer I know has burned out at one point or another. I think it would be helpful to talk about why we burned out and what brought us back.
RidgeRacer, I'll give you the benefit of my experience for what it is worth. During my longest break I sold my cars, radios, batteries and motors, but kept my tools. All told that was a fairly good idea with one exception, I would say keep your first car, keep your favorite car and most importantly keep your tools! Other than that if you're stressing about how much you have tied up in it all than go ahead and sell it. For me one of the attractive aspects that brought me back to the hobby was how much the cars had changed and how cool some of the new cars and technology were. That Christmas feeling when buying new stuff is always a good thing.
As far as racing goes, I have a mantra "We're racing little toy cars." If that doesn't make me happy without being stressed out than I know I'm in the wrong place in my head. This is a hobby and while it has many challenging and redeeming facets, generally it should be stress free and fun! If you're not having fun don't be afraid to take a break, but don't write it off either. Space and time allow for a broader perspective and once you think of those really cool, really fast little toy cars again you can discover it anew and hopefully find a different satisfaction from the experience.