2005 Pathfinder shakes during accel after 40mph

[bigmisiu]

So, we've got about 120k and it starts to shake when attempting to accelerate after ~40mph at a normal pace. However, if we ease into 40mph-55mph really nice and steady, any vibration is minimized to a point where you can't really detect it but it's still there. If we floor it or accelerate normally at any time (+2000 rpms) the vibration issue occurs.

Any ideas?

[NismoPick]

CEL codes? Checked the tires? Suspension? Have you "looked" at the car at all?

[bigmisiu]

My wife does get a code that pops in every week or so that has to do with EVAP canister valve I believe. I had it checked at autozone once but can't remember details at this moment. Tires are old. When I let off gas the shake stops.