OK, I swear I have this figured out now... When I was looking for my IAC (found it), I noticed that two hoses were just kinda hanging and not attached to anything. I hooked them up to what looked to be brass-colored pipes, and the sound went away - problem solved! HAHAHA, yeah right. Sound went away for about 50 feet and then it was back, with a CEL! The code is p0401. From searching, I've come to the following conclusions:
-p0401 = EGR flow insufficient
-those two hoses are vaccuum lines that go to the DPFE
And here's more, I've also had p0420 = Catalyst Efficency Below Threshold (Bank 1) as a CEL for awhile now. Before anybody tells me to gut/replace my precats, it's a Zetec, so no precats. From searching, I'm actually starting to see a connection here between a plugged cat and blowing those hoses off of the brase pipes. This is what I'm going to do:
-Replace both 02 Sensors (I got 'em, they'll go in today or tomorrow)
-Clean MAF
-Clean (or replace) IAC
Also, I clearly need to replace both hoses, as they won't stay on anymore, and one is cracked, plus god knows what's gotten sucked into them over the last 1,000 miles. However, is the DPFE gonna be OK? AND, how can I test to see if the CAT is clogged? You're suppossed to hook-up to a nipple at the DPFE, but with those hoses off, is there any other way to check that? Or, am I completely offbase and actually have an entirely different problem? Also, just in case I'm entirely off, here's a picture of the stuff:
