Dogday, Jack, and Belloypilot ..... Hi !
I've checked EGT probes (thermocouples) for relative position and calibration. Agree totally that EGT is not an accurate metric in absolute terms but in relative terms I see it as an indicator. My CHT's are relatively even and stable with roughly a 40-50 degree delta between them. I'd like better but they do also follow the EGTs.
Belloypilot, you make a good point and no I've never followed which cylinder peaks first etc. In actuality I rarely lean because I'm trying to manage the one EGT to stay below 1400 and don't have the bandwidth to lean.
A while back Thomas suggested the pushrod lengths on the hot cylinder could be too long. I would never have come up with this on my own and am in the middle of checking it now (we have a week or two of lousy WX so no flying). I'm doing the "dry tappet check" and have gaskets and retainers on order so it will all go back together with new pieces. I'll post results of the clearances when I have them.
If I find a "smoking gun" with this I can move on. If not I'm back to the airbox