Is there any dyno nearby that you can take this thing to? At least get a baseline of what you're getting at the rear wheels with your junk now; badly tuned or otherwise.
Besides following all the endless good advice in this thread, that dyno report would give you a visual graph of the engine's power (or lack of it), indicating any lack of power in a particular RPM range where it falls off.
If you want to approach this as a science and not take any words for granted, measuring horsepower by butt dyno and torque by burnout is not good enough here.
-Kurt
