hiccup or hesitation when cruising

Hi, I just bought a '05 Odyssey, 50K miles. I noticed a slight hesitation or hiccup when cruising, very slight, but noticable and very annoying after awhile, took it back to the dealership and they said it was the EGR valve and replaced it. It has improved to some degree, but still does it, is this normal for Odysseys? Is this due to the ECO mode and this is when it drops cylinders that I'm feeling? anyone else notice this issue?

thanks, for any ideas, mike