I agree, all kitfox's should have no issue at that altitude or with a 30 degree temperature change.
I think I figured it out, I did try to check the prop pitch but I can't find the instructions for the protractor and I didn't realize until I got to the airport that I did not know what the hell I was doing.
I checked the Jets and the main jet is a #170 and the idle jet is a #55. The Needle Jet was set in position 4, full rich, so I readjusted it to position 3 and we will see how that goes.
I also ordered a #160 Main and a #45 Idle Jet. We will see if that helps raise the EGT's back into the 1,000-1,200 range.
I called the previous owner, the reason for the #170 main jet is the airplane had a GreenSky HACman kit on it! He removed it and THREW IT AWAY because he didn't understand it!!! He neglected to tell me this or put it in the logbooks because he did not feel it would have any effect on flight performance! Now I'm worried if he did anything else to the engine or airframe without logging it.
I'm going to check the prop pitch but I don't feel like it's going to be a problem. It flew fine a few months ago when it was last flown, seemed to climb around 500-700FPM and cruised at 80MPH. I can't it's too far off.