Update:
OK, pulled the header and no evidence of coolant 'jetting the ports'.
I have attached pix of each port, Right to Left facing the ports. Please take a look and comment if you see anything unusual that I may be missing.
Now I'm still confused because this seems to point to a too rich mixture yet NO FOULING of the plugs.
Some things that the previous owner did that may or may not be helpful in diagnosing this weirdness:
1) said he put some seafoam in the tank. I have since run it nearly empty and refilled 3x since I bought it.
->could the carbon fouling in the exhaust ports be tail end of carbon residue being cleaned by the seafoam?
2) Put in a new O2 sensor (the one that is now fouled).
->when I bought the car I drove it for about 800miles before I replaced the plugs from ZRF5-11's to ZRF4-11's and pulled the O2 sensor just to look at it. Plugs were very clean but O2 had a bit of carbon fouling. Didn't think anything of it at the time cause this was my first VX. Cleaned off the carbon (just from the outside of the tip, carefully) and checked again when I bought a spare O2 sensor off eBay and wanted to test it. Carbon fouled again. Cleaned it off. Checked plugs again, still spotless. Drove 40miles, pulled the sensor and again, more carbon. Guess the short winded version of what I'm trying to say is that it get fouled very quickly.
Possible head gasket from 2 owners ago:
-> could a HG leak cause carbon fouling ONLY in the exhaust ports and beyond?
Right now I'm getting a CEL for the O2 sensor and getting *maybe* 28-30mpg. UGH. Don't want to put a different one in there if it's just going to get buggered again.
Where to go from here?
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