Ok, I am completely lost. The issue began with high idle (2000-2500 rpm). The CEL came on, and codes indicated IAC, and misfire 2 and 5. I treated this as two separate issues. I changed the IAC, and idle dropped for a day or so, but high idle returned with no CEL. As for the misfire issue, coil pack and wires are fine, but the plugs in 2 and 5 were extremely corroded. I changed all the plugs, and I did a compression check at the same time. All cylinders showed 150 psi, except 2 and 5. Cylinder 2 showed 140, and cylinder 5 showed 170. At this point, after new IAC, new plugs and wires, and several questionable vacuum lines, high idle remains and the misfire is noticeable, but no CEL.
Things I have tried:
I vacuum tested the egr, and it operated fine.
I sprayed vacuum lines/intake with brake cleaner-no idle change
Removing the wire harness to IAC-idle drops briefly then elevates
My next plan is to remove the intake and begin testing injectors. Any advice would be greatly appreciated.