Seeking assistance with a Yamaha generator EF12000DE, unit has 20 hours on it. Changed oil and filter, fresh gas, removed, disassembled carburetor, cleaned and reassembled, installed. fuel cut off solenoid and oil pressure switch replaced with OE Yamaha. This unit will run at idle and half throttle. When full throttle the generator will for a few seconds and dies. Restart at idle not a problem. Oil level is good. Any help is appreciated.