Well I bought my Focus from a Honda dealership (I know it makes no sense) and made an appointment with the closest Ford dealership to my work. They took it in with no questions asked and ran the recalls. I did explain to them I wasn't the original owner and wouldn't have received notification of the recalls and they were fine with that as the car is still under warranty and transferrable.
suss6052, I can't begin to understand the exact mechanics of an engine and its behaviour but it did seem to help. I will make sure to keep close attention to the scenerios you described to see if I will experience the shaking again.