Been looking for a new car but yesterday my current Prius (200,000 miles) started misfiring and shaking pretty violently. Coolant level seems fine. Misfires happen at idle and light acceleration. under heavier acceleration the misfire is not noticeable. Started a mile or so into a 75 mile trip and continued the complete trip. Pulled the codes and got 0301, 0300, 0302, 0301, 2190, 2190. The potential for head gasket failure is the reason I was looking to get rid of the car. A search here for the P2190 code came up blank on the forum. If an easy repair can get this car running better, It might be worth it rather than trading it in the way it is.