2000 Lincoln Navigator - few days ago started idling very rough when truck is at a stop or in park. Service Engine Light came right around time I noticed that it was idling rough when stopped. Following codes came back P1131; P1151; P0171; P0174; What could be wrong??

Get a scanner connected to see what error code is throwing. It's where I would start.

Sounds more like an engine idle issue than a oil pressure issue. If the engine idle drops too low, the oil pump cannot provide sufficient oil pressure. If there is no oil light when the engine is idling normally, then there is no problem there.

Do you have a "Check Engine" light?

Check the coils in each cylinder. At 140k the valve cover gaskets tend to break and oil will fill the coils causing misfires and stalling.

faulty idle air control valve is your problem

Change ur spark plugs and your coil packs - its time!

Any time that the check engine light comes on, it indicates that the computer has found a condition serious enough to require service action. Rent a scanner, read the code(s), and pursue to repair(s). The scanner will clear the trouble light when the repairs are complete.

i had the same trouble, there is a rubber boot under the cover on the top of the motor, it is coming from the egr valve, takes about 5 mins to repair and less than 5 dollars.

Has your engine gotten wet? Sounds like water around your spark plug boots down in the port around the spark plugs. If there is any water down there, make sure you blow it out with air compressor prior to removing plugs, or it will drain directly into the engine. Another scenario, could be EGR valve or related parts.  Is your check engine light on? With that rough of a ride, it should be. If it is an auto parts store should be able to read the code to help pin point the problem. Good Luck!

here is a diagram of the map sensor #5.

Bought a use 03 last week for very cheep because it was idling rough, read in a forum about focus vacuum leaks and to use small burst of starting fluid to find the leak, spray around engine, if you hear the engine level off and run smooth in a particular spot for a few seconds the leak is in that general area, check the hose in that area, i found a large elbow on my pvc valve line was cracked in half, repaired with copper plumbing elbow fitting and silicone. now runs perfect. be very careful with the starting fluid short burst in well ventilated are.