The entire block under the truck has oil covered in it and my oil pressure sky rockets when I start my truck and sometimes goes down when I drive but usually comes back up and was wondering if my gasket was worn out and if this could be the problem?

 

5.9 cummins are oil leakers,especially from front cover and lifter cover.

 

If its oil leak problems and notice huge puddles of oil under your pickup then mosr likey it the tappet cover gasket.... those thing rot like no other... but the oil pressure thing might just only be your sender. Try getting a new one there like 80 bucks or so.