98 ram 5.2 help needed

If I were you I would definitely replace the plenum gasket first, I have had alot of these trucks and they all need it sooner or later. If there is no noise, chances are the lifters are fine. Sometimes its better not to mess with things that aren't broke, so leave them alone unless you see something wrong when you have the intake off. You didn't say how many miles are on the engine, but I changed the timing chain on my 2000 durango 5.9 at 273,000 miles and it still would have gone further, for what its worth.