Percolation? Heat soak? Don't drive during summer??

That temp isn't bad, IMO.

The next thing is: running that same intake, I had a similar result. Add on temp sensor would read over 205, factory gauge read in the middle. Here's where it gets strange: my IR temp gun would consistently read 195 (thermostat temp) all over the manifold. I could never find anything hotter than 195. My only guess is that there must have been a small pocket of air I couldn't get out..

When I went to my efi system, it was similar. Originally I did not have the right pipe thread adapter to install the temp sensor in the manifold, so I just laid the sensor in the valley of the intake. It worked great, in fact. Always read a max of 195. As soon as I put it in the intake it would match my autometer gauge at 204-210 depending on conditions :BangHead:

Like I said, the only explanation I could conure was an air pocket, maybe. I did swap ports too, didn't change the behavior.
Could be that there was a stream of hotter water coming from the heads that wasn't necessarily the same as surrounding coolant? Hard to say, but that was my experience.

I've since swapped to a Victor 340 and the operating temps are still 195-205 (195 stat) but I haven't rechecked with the IR gun yet. Wish my thermal cam had a direct temp readout (only shows heat relative other surfaces).