lunges forward, rough idle, acceleration, vibrations

Been having a lot of problems with my 2007 Mercury Mountaineer with 130,000 miles. At first, thought it was transmission problems until hooking it up to a computer to read P0446. Evaporative Emission Control System, Vent Control Circuit malfunction. An engine vacuum leak. Needing honest opinion. I know it's very time consuming to find a vacuum leak so just wanting to know the most common places and start there. Also, every article says it needs to be fixed asap before damaging the engine. This is my everyday work vehicle, need to know just how serious this is before spending a ton. And are all these symptoms of the leak or something else? Accessive fan blowing (sounds almost like a rocket ship and just recently started), acceleration problems, the vehicle shakes non-stop. When pressing on the brakes, driving fast, and driving slow. Horrible gas mileage. And it lunges forward and RPMs shoot up when I'm almost to a complete stop every single time.