EGT CHT High temps

[WebMaster]

Was over at Meigs on Sunday, and on Monday we left. 69 337D, normally aspirated. When I started the engines, shortly there after, the rear engine EGT went up, close to where i run it at 50 rich of peak. Standard Cessna Gauge. No actual temps displayed.
Mag check was normal.
My initial impression, was that it sat out, overnight, humid lakefront enviroment, I got moisture in the gauges, or something.
Take off, slightly less MP than front, but that is normal. However, seemed to be less than normal. However, very High surface temp and humidity. Don't know how much of that was the cause.
EGT stayed where it was, throughout climb, and if I leaned it, it got higher, but at cruise, fuel flow was pretty much normal. We have Shadin Digital, and EGT settled in to what is normal.
Landed in Kalamazoo, dropped my wife off. During approach, EGT dropped down, in a fashion that I would call normal for approaches. A few minutes on the ground, headed to Grand Rapids, where I keep the plane. EGT showed the same as Meigs, high, and oil temps were up, both front and rear. Again, 90+ Outside air temp, and lots of humidity. Climb performance was same as coming off of Meigs. Slightly lower than "normal" MP. Level off, and everything gets to where it normally is.
Landed in Grand Rapids, and EGT stays up, slightly, and CHT stayed up a lot.
Took the rear engine covers off, today, and looked. On the rear engine, there are little exhaust pipes that connect to a collector. There are little clamp sort of things that make the connection. The collector goes to another clamp thing, that is spring loaded, and thence to the muffler. On the right side of the engine, where the single EGT sensor is, there is evidence of escaped exhaust gases, yellow stuff, at each connection of the pipes.
There are, to my feeble mind, 2 potential causes.
1. Somehow, I am running very much lean, especially on the right side. (fuel flow does not bear that out, because if anything, I was running at tad bit rich on the rear).
2. I have leaky exhaust, which is causing the EGT sensor to malfunction. It appears that the cht sensor is also on the right side, so if I have leaky exhaust, that is why CHT was high when I landed.
Your thoughts?
What is the fix?

Thanks as always.