You may be right, its hard to say without being there and looking at it. Look at the spark and see if its weak/strong, you should see a nice pinkish/purple spark and it should be able to jump around a half inch gap or so. Your problem sounds like it might be a fuel concern or weak ignition system but sounds like you have a good fuel supply. Maybe check the coil and spark quality, wires, cap and rotor and ignition timing.
Check the obvious stuff too like air filter, and throttle linkage to see if you are getting WOT, make sure the choke plate is not sticking closed. Also its possible that the fuel filter could be stopped up from debris in the tank or dirty/bad fuel.