The deflector on the front of the cylinder is definitely a viable option. Somebody else on another similar thread suggested putting a nut plate on the underside of the front baffles so that the deflector can be easily removed with a couple of screws for fine tuning adjustments. Not my idea, but I think it's a good one. FIXIT is describing a another quick way to address this as well.
Do you have a plenum or a standard Van's cowling with baffles resting against the cowling top? If it's the latter, the air flow past the top of the D-shaped inlet can be disrupted during climb if the transition to the top of the cowling wasn't smoothed out with fiberglass. That may account for the temperature differences between climb and cruise. If yours just abruptly dumps air in there, do a search for how this should be done, or review Van's plans. It can make a big difference. One of the smarter engineers here can chime in about pressure drop, energy loss, delta P and all that. My overly simplistic explanation is that the air flowing into the upper portion of the engine needs to flow smoothly or it will adversely affect cooling.
