For 1990-2009 cars

Cause | Correction
--- | ---
Worn or loose valve rocker arms The rocker arm bearing needle bearings should be intact within the rocker arm assembly. | Replace the valve rocker arms as required.
Stuck valves Carbon buildup on the valve stem can cause the valve not to close properly. | Repair or replace as required.
Excessively worn or mis-aligned timing chain | Replace the timing chain and sprockets as required.
Worn camshaft lobes | Replace the camshaft, valve lash adjusters, and rocker arms.
Sticking valve lash adjusters | Replace as required.