There aren't any oil ports in the head gasket to receive cylinder pressure. The top end is oiled through the pushrods.
Speaking of the top end,O.P. is there oil coming out of your pushrods? What is your oil pressure?
If it isn't the filter itself i would think a blockage in an oiling passage or stuck bypass in the pump. Swap the filter and check the oil pressure with a mechanical gauge like this one.
View attachment 654813
Yep,cheap and easy way to check,especially if you have an 03-06.(fake oil pressure gauge)i don’t think I’ll ever use another FRAM.
