Need help with spark plug diagnosis

[alkon]

I have a 91 Camry LE with 190k miles. Recently, it has been idling rough and gas mileage has dropped. I checked the resistance of the plug wires and they all fall within specs. When I looked at all of the plugs, I noticed that #1 had the appearance of carbon/oil fouling. I have great compression in all cylinders (170-175#) and I did a leak down test in all cylinders and they test out well. The appearance of all of the other plugs is normal. What could be causing this one plug to appear fouled? I am guessing that the cylinder is running too rich. What do you think?

[fredk]

valve stem seals maybe, got a pic?

[Doctor J]

Could be also leaking injector number one