2000 Expedition Rough Idle and Stalling

[Mad Dawg Wiccan]

That sounds exactly like what happened when my EGR valve had a leak.

[tskeeter]

MM, if replacing the PCV hoses don't fix the problem, I'd look at a possible EGR valve problem, as MDW suggested. The symptoms sound very similar to what I experienced on a car with EGR problems. Car would idle OK, but would stumble and stall when you stepped on the gas to pull away from a stop. The car would also run at driving speeds. The problem I experienced began as an intermittent issue, then got progressively worse. Problem didn't show up on the initial diagnostics, so the mechanic drove my car home to see if the problem would show up. It did.

On the up side, my EGR valve replacement was covered under the 100K mile emissions warranty.

[tskeeter]

So Rick, make me a little smarter. I get that the exhaust sensor can go bad and report incorrect information to the diagnostics system, setting trouble codes that are not valid. So how would that cause engine performance problems such as what MM has described? Is the sensor also sending the incorrect information to the engine control computer?

[Mad Dawg Wiccan]

I dont think her problem is an EGR problem. What she has going on is a vaccum leak, sucking in unmetered air.

The only reason I mentioned the EGR valve is because mine cracked at the base, creating the vacuum leak. It was so loud that at first I thought I had sprung a radiator leak.