For 1990-2009 cars

Cause | Correction
--- | ---
Worn or loose followers (valve rocker arms) (The follower (valve rocker arm) roller bearing should be intact and in the proper position.) | Replace the followers (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(s) | Replace the timing chain(s) and sprockets as required.
Worn camshaft lobes | Replace the camshaft(s) and SHLAs (valve lifters).
Sticking SHLAs (lifters) | Replace the SHLAs as required.