I have a 200 Camry V6, which I haev just learned is known for its sludging. I believe 1999-2002 are the years? My car has three coils. On each coil fire, two spark plugs actually fire. These engines use a strategy whereby each cylinder is sparked not once but twice per cycle--one for the power stroke and one in the exhaust stroke, to burn off any unburned fuel. My mom has a 2003 or 4 Avalon with the exact same engine, but with 6 coils. Could it be that the years known for sludging coincide with the exhaust scavenging spark technology? Could the extra heat generated by the extra spark be the culprit? It's a stretch I know.