Check Engine Code: Exhuast Gas Line

[joelefors]

I've had the check engine light on for a while on my 96 Sentra. It was idling a little rough (kinda low)

At first, my mechanics OBD said it was the idle control valve so I replaced it with a newer one from the junkyard and that improved things. Now it idles a little high. The check engine code now says that there is something wrong with my exhaust gas line or EGL. How should I go about diagnosing what I need to fix/replace?

I believe there are 2 EGL sensors? Should my first step be replacing those?