I've been hearing an audible clicking sound at idle on my wife's 99 Durango (5.2L) for quite some time. I took a screwdriver and pressed the blade over the valve cover and put my ear on the handle, and from what I could tell, it sounded like a lifter causing the clicking. Has anyone else run into this and are the lifters easy to replace without tearing a significant amount of the engine out to get to them?