Car shakes when idling and accelerating

My car shakes occasionally (when idling and accelerating). Every once in a while when I turn my car on it starts shaking and when I start driving, it is as if the car lost half of its acceleration power. Sometimes the idling starts in the middle of the highway at high speeds and other times its right when I start my car. It accelerates really slow (while slightly shaking). Sometimes I pull the car aside and turn off and start the car three to four times and the engine somehow works itself out. I think there is a problem with one of the pistons. A few times the shaking did not stop itself so the car started smelling like rubber. I pulled it over and pulled the hood up, and a few seconds after the engine cooled down I heard a "clink" sound which sounded like a metal wire pulled on another metal piece. After the clink the car starts normally and I am on my way with no shaking. When the shaking starts both the inside and the outside of the car smell really bad. How can I fix this? Go to a mechanic?