Hi New member here just dropped my intro in the new member section!

I just purchased a 2006 Express 2500 Van it has 220,000 miles but looks VERY well kept and was a one owner vehicle. I normally don't buy 3/4 ton vans because the contractors that generally use them beat them to death then sell them.

The oil pressure fluctuates and is low once the engine is warm and the lifters will start to chatter but not all the time... this is what has me stumped. Normally you either have good pressure or you don't... it doesn't come and go at least in my experience.
On a google search there was a link to a forum and one of the members said he had "stuff" (sludge, etc.) floating around in the pan and it would block or restrict the pickup at times sounded a but far fetched to me but possible. I was thinking along the lines of a stuck bypass valve or broken bypass valve spring.
Or is it possible that the pump is worn and just needs replacing?

Thoughts?

I have attached a few photos of the truck... as you can see it is in excellent condition and I would assume the engine, trans. were serviced the same.