Ian,
I had a 582 several years ago and had the same problems as you with no web forum to help me. To make a very long story quite short, the overheating problem was airflow through the radiator. Even though my radiator was mounted per the Kitfox manual, I had to lower it 3-1/2 inches in order to get enough air flowing through it to provide cooling. Easily done, but maybe not your problem.
As for the RPMs being too low, I ran my engine for 130 hours until it lost a rod bearing. With a new engine, gearbox, and prop, I had the exact combination as called for with the prop setup instructions. I pitched the prop exactly per their instructions and had the same low revs. I had to pitch the prop much flatter to get the correct RPMs. After about 10 hours I decided to set it up exactly per instructions and fly it. Wow! It climbed out much better! I acquired a model airplane handheld tachometer and checked the revs with the new setting. I was then getting the correct rpms. My panel mounted tach was off by quite a bit. I plotted a curve using the corrected revs and found I had been taking off way above red line and cruising right at red line for 130 hours. All because of a bad tach.
Check your tach.
Alan
