Sounds like you might have an issue with your engine itself. A couple quick fixes you might try, include a thicker brand of oil, or perhaps even changing your gas to a cleaner burning brand.
If you have a very bad knock inside the engine then more than likely it has severe internal damage. This means that if you keep driving it it will throw a rod or seize up. You need to have it properly rebuilt and the damage fixed.
During your next oil change assuming you do it yourself after draining out the old oil fill it with 6 and a half quarts of ATF+3. Run the vehicle for 5 to 10 minutes at 2000 rpms. Drain out ATF and change the oil filter. Fill with oil. This removes built up carbon which 70% of the time causes knocks.
The Intrepid has a history of knocking from its low quality rocker arms . This is an expensive area of repair and time consuming. The other place of concern for these cars is the piston rings, by history the Intrepid rapidly destroys rings and causes multiple problems down the line
If a car is knocking very badly then it probably has severe internal damage. You should take it to a professional mechanic before it destroys the engine. Chances are it will need to be rebuilt.
a hard knock would indicate that there are piston or crank shaft problems whichare catastrophic.u may need a new engine.u might try to change oil.repairs maycost more than caris worth
