I've got a 2000 Toyota Avalon with 165K miles. It's been well maintained since new. It was my father-in-laws car (his first new car) and I've owned it since the odom. showed 100K. Decent oil change history. 4-6K OCIs depending on the highway usage. Ran an auto-rx dose through at 110K. Been running a maint. dose ever since. Since the nasty cold spell last month, the car has been throwing the following codes: P300 mult. misfires P302,304,306 misfires cylinder 2,4,6 P1354 VVT-i malfunction bank2 Then last week a new code also occurred. P1351 VVT-i sensor range bank 2 The car has sometimes sputtered at idle a bit. At one point, it seemed like the power brakes were strangely stiff. Everything has returned to normal except for the codes and an occasional sputter at idle. I've changed the oil. Penzoil YB 5-30 with one bottle Valvoline 5-20. I ran some seafoam through in a full tank of gas. I haven't had real look for sludge yet. Most of the normal maintence has been done by me. (Fluids, belts, plugs, PCV.) I'm thinking some or all of the following. A bit of sludge on the timing sensor (or bad sensor.) Some ice/ water in the oil. A partially blocked VVT oil screen. Anyone have some tips for me as I figure this out?