1998 Subaru Legacy 2.5 GT ticking sound?

Sounds almost a rod knock but goes away at about 2800 rpm. I've heard that in '97 they switched to a hydraulic lifter and needed to have the valve reset every 100,000 miles. The car is getting close to 140,000. I don't know if that's true or not, but if not what else could the sound be? It sounds like it coming from inside the motor somewhere. I have no clue where anything is in the motor, I've never worked on a Subaru before other than a motor swap. This is the cars second engine and i'd really like the keep it alive this time. I know these engines have a thing for dying.