OK , back to the problem. Andy, do you have a thermocouple reader? (sorry if I missed it in the thread) I have some fuel issues on my IO360 hot as well. I am not sure mine is temperature, but have been measuring some points to understand it. I made some K type bead thermocouples by stripping and sticking the twist into a TIG flame to create the beads. They will slide into a slit in the fire-sleeve to get a bit closer to actual fuel temps in the teflon hose. I found what I think are elevated temps at the firewall bulkhead fitting. There are too many points that need to be measured at once, so I have not progressed in this project, but will measure the temp rise from the entry from the wing root to the bulkhead fitting to see how much the rise is coming from inside the "tunnel". I don't remember all the temps involved, but was really surprised that the bulkhead fitting inside the cabin was so hot relative to what I though the tank was and ambient temps. +15F is my recollection.
Anyway -I would suggest temperature measurement of the fuel might be very helpful to this process.