djb you are correct as before crankshaft on bottom cam cylinder head lifters slide down on top of cam inside block pushrops on top of lifters come up to rocker arms inside valve cover rockers push down on vavles to open and close since rockers on top of engine dont always get lub they need sometimes they make noise all better now

 

your more than likely correct on it being the lifters. seeing as how i have a 98 chrysler sebring dead in my yard with the same problem among a couple others. if its a knocking while idle aat a slower rate that some what matches your idle than increases as you rev the engine probably a lifter. Best way to check found a back road with a gaurd rail so you can hear the echo and just try different engine speeds.

 

The lifters in mine start tapping louder to tell me it's time to change the oil again! It's always noisy, but sometimes it gets loud enough I swear it has to be a rod going, but change the oil and it's back down to a tick again every time it seems.