I already ran a search and although it pulled up 2 pages worth, most of the threads were about the 5.4 or the 4.6L. I've already cleaned the maf, replaced the fuel filter, cleaned out the egr valve and it's inlet area, then reset the computer. After a few miles it came back on and i'm sure it's still the same codes.

Is the 4.2L affected by the vacume leak on the PVC valve like the v8s? Is it also located at the back of the intake? I couln't find it but i'll try and look for it tomorrow.

Thank you guys in advance for any help.

 

If it's not the MAF then you likely do have a vacuum leak somewhere.

The PCV valve itself is mounted on the passenger side valve cover, towards the back. The hose runs from the PCV valve to the underside of the upper intake manifold, behind the throttle body. It certainly is possible that the hose is cracked or it may have even come loose and fallen off the intake manifold. If it's cracked, I don't think you'll have an easy time finding the crack. This hose runs through some very tight spaces under the uppper intake manifold. The hose at the front of this photo, running to the left rear of the engine, is the PCV hose.

Also check the crankcase breather hose. This runs from the driver side valve cover to the air intake tube. Make sure that it's secure and not cracked.

Another source of an airleak on the 4.2L would be the brake booster hose. This runs from the firewall to the underside of the upper intake manifold.

 

Hey I have chased down vacuum leaks myself. There is a culprit that can drive you crazy. Back behind the battery tray between the battery tray and the firewall is the main vacuum tree. The main manifold branches off into all the little vaccum lines. These are leaky little pains that cause all sorts of potential codes. I didn't look up your codes specifically, but any mention of vacuum raises the redflags to me for this area.

What you need to do is remove your battery and the tray. The vacuum tree is basically right at the bottom of that area (imagine where battery acid can go and that is where Ford put it). You will need to seperate the lines from the loom in order to inspect them all. They are of different colors but all are checked the same. After you can visually see the individual lines you simply check for holes. Mine looked like Swiss cheese (tiny little pencil lead sized holes) and you could physically hear the hiss when you had it in front of you to test. I'd check from the main manifold connect point down at least 6-8 inches of travel into the bundle. The battery acid is what causes the leaks and its usually contained in the first several inches I spliced in new lines and not only solved my codes, I ended up solving an intermitant rough idle and stall problem. I also got some lost performance back. These engines are very dependent on a good tight vacuum system.

Good luck and if I can be of any more help just drop a line back here.