Got my engine back from being rebuilt and it is set up to double oil for the break in period. I have kept the motor trimmed down to keep a load and veryed the rpms every 2 minutes or so and keep the rpms 2800 to 4500. Every once in while I'll pump it up to 5000 to 5200 but as soon as it hits this the motor starts slowing down and if I hold the throttle wot it will slow to 4000 almost like its going into gaurdian. Is this normal?????

kent