I HAVE A 1990 JOHNSON, VRO DISCONNECTED AND MIX OWN OIL/GAS. PROBLEM IS IF I GO OVER 4000 RPM THE OVERHEAT HORN SOUNDS AND ENGINE SPITS DOWN TO ONLY RUN AT IDLE SPEED. I HAVE HAD IT RUN ON DYNO MACH AND WAS TOLD IT WAS TAKEN CARE OF. I AM MIXING 50 TO 1 FOR OIL IS THIS SUFFICIENT? WOULDN'T IT OVERHEAT AT 2500 OR 3500 RPM AS WELL AS OVER 4000? COULD IT BE A FUEL SUPPLY PROBLEM?<br />THERMOSTAT HAS BEEN REPLACED AS WELL AS WATER PUMP. WOULD APPRECIATE ANY SUGGESTIONS.