Buildup in Exhaust Ports

[awdseegs]

Good morning.

I recently acquired a 1992 1G AWD. It was someone's project car that had been sitting for a while. I had begun to notice oil pooling around the #4 exhaust port and seeping around the gasket as well as an exhaust leak.

Observations/Facts:

• The car has been running incredibly rich.
• The car has idled for a number of hours while I tried to learn DSMLink and get the idle stabilized. I did the get the global fuel at -60.
• I have not noticed blue smoke while idling/startup.
• The head has been off before, but unsure how long ago.
• I have observed some small amounts of oil pooling under the COP plate--I have read that the valve cover gasket failure can cause oil to seep into the exhaust ports.
• I will do a leakdown test later today.

I have attached a few pictures that I hope I can get some feedback on. I have cleaned the gasket mating surface a bit in the closeups. The zoomed out picture is pre-cleanup. I appreciate any help from the DSM community. Thank you.

Question:
Is this due to the excess fuel? A leaky valve cover gasket? Bad valve stem seals? All three?

Mods list that I know/can think of:

ARP head studs
JMF Intake Manifold
20G
1050 Injectors
Adj FPR
HKS 272/264
FMIC
Greddy BOV
Full 3" exhaust
DSMLink
Speed Density setup
Innovate Wideband Sensor
GM IAT/MAP Sensor

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