so I need to pull the lifters that have an issue and clean them? Is there any parts inside that should be changed or do they just get replaced?
I'm dropping the ball all over the place man, sorry!
No, there are no parts inside any lifter that are replaceable.
Let me make that a bit more clear...any particular lifter was set up at the point-of-manufacture with "selective fit" guts. And after many thousands of miles of operation, each one is worn in to it's respective internal components and camshaft lobe. So we never want to swap internal parts around, nor, swap a lifter away from it's original installed position. This is a basic tenet of engine work, even when working with so-called "solid" lifters that are used with an adjustable valve train.
Also...on the oem side, ihc used over the years at least two vendors for lifters for all I-4 and sv applications, those are identified very well in the service manuals which have extensive information regarding dealing with hydraulic lifters in general. Using that information you can see how each lifter was I.d.'d originally, though they are interchangeable form one engine app to another as a set, the individual components which make up each lifter do not interchange.
On occasion I carefully disassemble and clean each lifter if it's base appears to be ok to re-use on the cam lobe it's mated to. This is not something normally done in routine engine service as no one will pay for having that kind of work done when it's far cheaper to just replace 'em.
But when you see what the inside of these items look like, you will soon understand how tedious they are and really appreciate how such a precision part can withstand total lack of regular oil change intervals and being allowed to remain stationary for so long! If the actual lifter base is ok, then a careful cleaning will bring 'em to life for a long period of time if oil is changed on a regular basis.
Some folks advise never using a new lifter on an in-service camshaft. But I have no problem with that if the lifters show only normal wear and the cam lobes show no wear at all. I simply treat 'em with assembly lube and stick in the hole, then run the motor for "break-in" as if both cam and lifters were replaced as a set. I've done that quite often over the years on my own stuff, I'm running one right now that has about 20k miles on it (392).