[EF You]

what color is the smoke?

first guess would be the PCV valve. if its stuck, you are sucking oil into the manifold, and that would explain the smoke when you punch it. its the simpliest and cheapest fix. if that doesnt work, look to your piston rings and your valve seals, they are the only other way to get oil into the combustion chamber.

if the smoke is whitesh, youve got water getting in, which could be getting sucked in because of a blown headgasket, cracked block, cracked head, or even a crack in your throttle body or Idle Speed Control Valve. check for coolant pressure with a pressure gauge and pump, if the system loses pressure too fast, and you dont see any coolant dripping, youve got an internal leak. thats a quick way to find it.

if its black, you are running too rich, try changing your ignition components, or cleaning your airfilter. those are quick fixes for that too. if it still smokes black, then youve got serious fuel issues.