Okay, gf's 06 Escape with 3.0 was running fine, no strange noises, she went to park at work, come out after work, starts it, it runs, but makes a sound kind of like a diesel. It runs, but poorly, have not tried driving for fear of damaging engine. Check engine came on, P0340. Replaced cam sensor since it's only $20, no dice. No other engine codes coming up, it starts right up, but horrible sound from engine. Sounds like it's at the top end towards firewall. My thought is timing chains, but just a guess. I'm going to take it in to have it checked. But first figured I would see if the collective knowledge here might have some ideas of what it could be.

 

Does the oil pressure light go out?

 

If the sensor is good, along with wiring, that leaves base engine issues as your cause. This is only further confirmed by the information you provide that there are abnormal engine sounds. First order of business is to remove the engine front cover to inspect what is not right and repair as needed.

 

So upon further inspection, the oil is low, thinking that could be part of it. I changed oil and filter, it's better, but something is still off. There is still some noise, but not as bad. When it starts there is a thunk upon starting, but then it runs, but noisy, idle is a bit erratic.

 

How low was it?

 

So finally get back to the car. I been out of town for work, so no time. It was low, like didn't even register on dipstick low. I added new oil and MC filter, it started, sounds better.
But here's where it is now. It starts, little engine noise, idle speed is okay, but after about 10-15 seconds it starts to idle down, almost like it wants to stall.

 

When you first start the engine, the cold idle speed, ambient in the 50's or even colder, should pop to above 1500 rpm... If the IAC is working. You can do a re-learn of the idle control by disconnecting the battery as I understand.
The 3.0 can/will suck all the oil out if the PCV gets stuck, from reports. I understand it can do that in one tank of gas driving range. Removing the PCV from the rear cam cover is not fun with the intake manifold in place. I found a deep socket that fits the replacement, and plan to use that to 'unscrew' the PCV from the cover as I could not get any leverage using pliers with the intake in place. The new one seems to have a heavy ball bearing(?) that flops around freely. The old? Dunno yet.
It could be you have a rod bearing on the way out, having been damaged by minimal oil pressure and flow. I would check all accessories for being tight, having pulleys snug on their shafts, perhaps even start with the serpentine removed to eliminate them from any noise sources. Check for noise as the engine warms. It could be your engine has bearing problems that will present more when the engine & oil are hot. The slowdown of idle speed could be the IAC not 'knowing' how much to open up to keep the idle steady after there is a 'change' in the engine.
Unless you want to drop the pan and inspect the bearings, you are taking the chance that there was damage which will not get better on its own. Clanky noises are indicatve of things being loose. My first thought until I got to the 'low oil' bit was the flex plate had broken near the hub, and was clanking, then the alternator/accessory of some sort being loose/damaged, then the cam chain tensioner... then read of low oil.
You could get a manual oil pressure gauge and screw it into the fitting above/behind the A/C compressor to know the actual. You can observe how quickly the oil light goes out when cranking, and if quick, how quickly it goes on when the engine is shut down.
tom
It is unusual to have noise just 'go away', so you may be covering the noise with lube that is thicker, not warmed up to operating temperature.