380SL just won't stop shaking.
 

Well, this car has shown some problems earlier, the engine almost stumbles to a stop at the light. Now, the car takes a long time to start, it won't start on first crank, and it rough idles badly, it gets slightly better when it warms up. My parents had the fuel pump and its relay replaced a year ago. I changed the plugs, cap, and rotor when they got the car. Is there anything else can cause this besides a vacuum leak?