have an intermittent fault for insufficient egr flow. safe to assume its the egr valve?

Or the vacuum hoses leading to/from the valve.

before you spend money, check all of the vacuum lines and such, but also try to clean the valve and tube. More often than not, a session with some gentle solvent cleaner (MAF cleaner) will free up a stuck valve or unclog a tube. I saved many people a bunch of cash this way at advance.

there is also a filter that can be cleaned and clear up a cell code. its in the UFO shaped canister to the left of the EGR valve.