My left side's been doing the same (turning gold) since day-1.

AI Removed (Day 1)
TOR Longs (Day 1)
Snorkel Removed Airbox/Filter drilled open (1000 Miles)
132 Mains (1000 Miles)
Idle-Mix 3 turns out

Plugs look good, so I guess I'll invest in a Carb-Synch tool.

Regards,