Id be checking and tightening all hose connections for the gas. My GQ was running dual fuel when I got it. It had a fully reconditioned carby, mixer, hoses etc. Twice over the period of 6 months I lost power with gas, also it wouldn't rev over 3000 rpm. Both times I fixed it by tightening the hose clamps on the gas line close to the carby. The problem being that when trying to get above 3000 rpm, it would begin to suck air in through the loose connections.

Sig test. android, MC version 2.4.7.11