So my car had a cylinder 3 misfire after a rough stall out(I was learning how to drive a stick) the car has had a check engine with a cylinder 3 and 4 misfire. I put new spark plugs in last night and the car ran great and the light did not come back. I was using the car and the engine began shaking heavily in an idle. I would hit the accelerator and the car sounded like it whistled. Any advice or recommendations on what could be failing? I believe it could be a vacuum leak. Any idea on what could be leaking any common causes?