98 xj engine noise

I have a 4.0. 98 with 100+k miles. I know this is a recurring question but I have a lifter sounding noise. Comes and goes. Loud and quiet. Seaford the oil and changed it. Worked for a day and back to the same issue. I know people say the flex Plat but how common is that? Is there anything else to look for? Could it just be a bad lifter?
Thanks for the help
Bgell