My Prius is a 2005 with 196,000 miles. Last week I had the oil changed and snow tires put on. Today it was 19 degrees. Not sure if any of that matters. This morning, the Check Engine light came on (steady - not flashing), and the car began to sputter when I would accelerate in low gears. The local V.I.P. Auto Parts store just ran the codes for me, and came up with a P0300: Random Multiple Cylinder misfire. Specifically, P0301 (cylinder #1 misfire) and P0302 (cylinder #2 misfire). They couldn't do any further diagnostics today, but gave me a list of possibilities. They also said the oil level is fine, and they doubt it's the ECM. How should I proceed? I'm afraid of running up a huge cost in just diagnostics? One simple thing they suggested was changing the spark plugs. Possibilities for the problem include: - short in engine wire harness - Connector / connection - vacuum hose connection - ignition system - injector - fuel pressure - mass air flow meter - engine coolant temperature sensor - compression pressure - valve clearance - valve timing - PVC hose connection - PVC hose - ECM Help?! Please!