Bubb2,
I think you might still have a fundamental misunderstanding of EGTs. The absolute numbers your EDM reports do not mean a thing, and you cannot compare one cylinder's EGT with another's to learn anything about either cylinder. Alcor, who invented the EGT probe, was so concerned that people would place undue significance on the absolute readings that they refused to even put numbers on their gauges - just a few markings so you could determine needle movement. There are many things that can cause virtually identical EGT probes to read very different EGTs for different cylinders. The hole for the probe might be 1/16" off, the shape (curvature) of the exhaust may alter the exhaust flow past the probe, back-pressure can slow the exhaust flow slightly, and a million other things can cause differences in absolute readings. But none of that matters, because even if one cylinder is reading 200ºF different than the other, it just doesn't matter...
What DOES matter is the "relative" temperature difference between EACH cylinder's PEAK EGT readings, and how much richer (ROP) or leaner (LOP) you are operating THAT cylinder from ITS peak EGT. Every cylinder will peak at a different EGT, and when you operate ROP you want to ensure that EACH of those cylinders is operating ROP. You have to observe all the cylinders, and note which one reaches peak EGT first. That is your "leanest" cylinder (at least that day, in those atmospheric conditions), and when you operate ROP you need to ensure that this "leanest" cylinder is running at least 100ºF ROP at lower power settings, 150ºF ROP at 65-75% power, at ideally at least 200ºF ROP when at full power (full rich mixture).
LOP operations are pretty much the inverse of that. You want to watch all your cylinders as you lean them, and note the LAST one to reach peak EGT. That is your "richest" cylinder (again for at least that day, under those atmospheric conditions), and is the one you will use to measure how far LOP you are operating... You don't want to spend a lot of time doing that leaning thing at high power settings, and the most common technique to get to the lean side of peak is the "big mixture pull" where you smoothly pull the mixture knob until you feel the airplane slow slightly. The feeling is similar to what you would observe if you were driving down a level road at a steady speed, and lifted your foot gently off the throttle. Just a slight "deceleration" is enough to know you're there. Then you confirm with your engine monitor.
You mentioned analyzing the data after you land to prove you were LOP or ROP and by how much... At that point, you're no longer operating the engine, so it does you no good to find out you were operating with some cylinders LOP and others ROP... You've got to be able to do that in the air. Most of the monitors have "lean assist" modes you can use to help with this. The better ones offer both "ROP" and "LOP" assist modes.
You might also want to check with your EDM manual to see if you can change the sampling interval to less than 6 seconds. Most of the monitors can do 1-second intervals, which will capture much finer-grained information for your post-flight analysis...
Good luck!