As soon as I turn on the car it is vibrating. It intensifies when I turn on ac. And most of vibration will go away when I turn ac off. It does not have the power it should and the engine light is lite and flashing. My air filter was very dirty but I replaced that.
It's pretty obvious you have a misfire. How long since the spark plugs and wires were replaced? With a misfire, a lot of unburned fuel and air will be going into the exhaust system where it will overheat and damage the expensive catalytic converter. THAT is what the flashing Check Engine light is telling you. It means to stop the engine as soon as possible to avoid that damage. There's is also going to be a diagnostic fault code stored in the Engine Computer. Many auto parts stores will read them for you for free, but in this case we can already guess the code is going to be related to that misfire condition. Continuing to drive the car is going to turn what is likely a minor problem into an expensive one very quickly.