^^Agreed^^ Clean your fuel system out first, and see what happens. However, I'm inclined to think that you have a bad parking brake switch on the handlebars. This switch is tied in with the TORS system, and if it fails, the engine will still start/run, but it won't rev properly. Such a problem will usually start all of a sudden, as electrical switches seem to pick the worst possible times to take a sh*t. X(
If you do opt to take out the TORS, this is fine, but do it one cautious step at a time. Clip out the throttle and park brake switches, unhook the leads from the carburetor cap, and tape up all the hanging plugs. You can peel apart the wiring harness and cut out all the TORS wiring at the actual crimp fittings, but this is a lot of work. I did it no prob, but not everybody feels comfortable ripping out wires. This 19-year-old kid must be the exception.
2003-and-newer Blasters have a unitized CDI box/TORS relay under the hood, instead of the two separate boxes used on older models. Once you get the TORS switches and wiring out (or taped-up), find the green wire coming out from the stator plate. These five-wire stators are used on the newer Blastys, as opposed to the four-wire units on pre-2003 machines. Anyways, unplug the green lead and ground it out against the chassis or engine. The ignition coil mounting bracket makes for a handy ground, but any paint-free surface will do. This extra green stator wire sends an electrical pulse, or 'signal', to the TORS control box. Grounding out the green wire neutralizes the signal pulse and allows the ignition to fire normally without the TORS circuit in use.