Hey, I have a 2013 FX4 5.0. 89000kms or 55000 miles. Never had an issue with the IWE. Grinds in 2 wheel drive when under load, when you normally lose vacuum. Had the tell tale grinding in an 08, replaced the one way valve and all was good. This valve is a bit different, but replaced it anyway, and it didn't fix it.. Pulled the supply line from the booster. Lots of vacuum, did the service side of the solenoid in 2 wheel drive, lots of vacuum. 4x4 no vacuum. back in 2 wheel drive, pulled the line off the accuator, one side then the other lots of vacuum. When I say lots, I mean I put my thumb over the line.. Jacked the front end up. Truck off, both axles locked in, as they should be. Start the truck, both free wheel as they should. 4 wheel drive locked in, it all works. It's acting like the one way valve is gone, but I replaced it. I don't have a vacuum pump, and hate to go buy one. Do the reservoir tanks fail much? On another note, has anyone had to replace the hard plastic line from the PCV valve to the intake? mine seems to be leaking. If I pull it off, the truck quits, but it seems to be hissing when it's on.