I was on my take off roll in the A-36 when I saw this indication on my Insight G-2 graphic engine monitor. So I aborted and coasted to the end of the runway and taxied off. The EGT on the #3 cylinder was way high and fluctuating.
After an engine run-up, there was no roughness and it turned out to be just a bad EGT probe as evidenced by the diagnostic page. Mission scrubbed but better safe than sorry. Its always better to sort this stuff out on the ground than in the clouds.