[olopezm]

Welcome to the forum!

First of all, the EGR valve rarely fails on these vehicles, so stay away from it! It's a expensive component. It is more probable for the DPFE sensor (part of the EGR system) to go bad and cause some misfiring problem but, as you said, only during cruise when the system is active.

I would remove the coil pack and take a look at the rear of it. It is a common problem and tends to crack at the epoxy insulation causing the spark to arc to ground. It is always more noticeable during wet days because of moisture in the air. You can test for resistance with an ohmmeter and pass the test but those small cracks will still give you problems.

Bottom line, if you see even smal cracks at the back of the coil pack, replace it.

Oscar.