The Lycoming o320 on my RV7a runs great at full throttle and mixture at peak. When I reduce the RPM in cruise, the CHT and EGT began to climb. CHT reaches 402-406 and EGT 1250 - 1400. Other cylinders stay pretty constant. Oil temp and pressure are normal. I have a cowl flap and that helps the cooling. I can't figure why temps would climb when I reduce the throttle and lower my rpms. 1200 hours on the engine. Any thoughts?