My 3.9L was fine during running but when i would let it idle the oil pressure would come right down. I took it in and the oil switch was shot. Could be that.

 

My oil pressure was dropping on my 3.9. i was going to change the sending unit, but I just wiggled the connector and the pressure has been staying normal.

 

I have heard on these engine that the oil passages a fairly small between the top and bottom of the engine and a little sludge can cause quite a problem by starving the top half of the engine. The prior owner being lax on changing the oil could be the cause.

 

so what should i do if the sludge is the issue? seafoam it?

 

That would be a start. The process is written up around here somewhere. It is usually pour a 1/3 in the gas tank, 1/3 in the oil and 1/3 down trickled down the brake vacuum line while running and cut it off and let it set for 30 min. It will hard start and smoke like crazy on start up if it is bad. You will want to change the oil within a couple hundred miles.

 

so swapped the oil out again this time with a more expensive oil (like it might help?) because i was goin through a timmies drive thru and heard a really obnoxious ticking coming form the motor! swapped it and seemed to be okay but now the tickings back ive heard everything about the 4.7 tick and now its really starting to get to me. i know i need new plugs i honestly dont think its been done since the last service it had at the dealship like 8 years ago, would this help any or am i gonna have to crack er open and swap out the lash adjusters and see if thishelps the noise/pressure issue

 

Swapping out the plugs will not do anything for ticking. Most likely going to have to swap out the lash adjusters and possibly the valves. Not real versed on this engine yet and it's problems but i know the valves can cause ticking on other model engines.

 

My 4.7 does both. I have the ticking on a cold start for a few minutes until the oil gets to the top of the engine, and the oil pressure fluctuates from the bottom normal hash mark to the top normal hash mark. Those lines signify the normal operating pressure ranges so as long as it's between them, I wouldn't worry.