If the noise you hear is a loud tap, then either the valve in question is still sticking sometimes, or you have a bad valve spring. Lifters rarely go bad and when they do, it usually causes cam failure and the engine will not run at all.
It could also be a bad valve guide.
There is an inspection cover behind the manifold that when removed will reveal the valve train. Remove it and start the engine and you should see the valves in action. Any issues should be visible.