3rd Gen Ram Tech2002-2008 Rams: This section is for TECHNICAL discussions only, that involve the 2002 through 2008 Rams Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
If you REALLY want to know what is going on inside and what the conditions are then connect a mechanical gauge to the engine and see exactly what PSI you are and how long it takes to build pressure. Then you will know if you have an oil pump issue or a oil pressure sending unit issue
Being a 4.7 I'm instantly going to say that you probably have sludge on the screen. Take the plastic baffle out of your oil feed neck and look in there and see if you have any sludge. If you can see some from there and you are already having oil pressure issues I would suggest that you take off the VCs and clean her up. You could clean the bottom end up also of course but that can get pricey if you don't have the tools or know how to do it yourself. Then a very important thing would be to clean your oil screen.
Not saying that it couldn't be other things but I would check for sludge first to eliminate that from a possibility. I found out my 4.7 had sludge issues a couple months ago I posted pictures on here the thread is titled, "found out shes a sludger" or something like that.
I forgot all about the 4.7s and sludging issues. Not having one, Ive never had the issue. Installing a mechanical oil gauge is not hard. You would simply (temp) take out the oil sending unit and screw in the mechanical oil gauge in its place.
IF you do have sludge and IF you want to clean the internals WITHOUT tearing the engine apart then there are products out there that can do it. Marvel Mystery Oil, Seafoam, some guys use diesel. But BE sure you follow the directions and change both the filter and oil afterwards.
I have used diesel before myself and had great results.