My knowledge is limited but i know one cause of the surging revs is an air leak. I meant to say check for air leaks around the EGR, e.g. a loose/broken bolt or a bad gasket. I don't know if a bad EGR will cause this but a leak around the EGR will.

As I said, if you notice the sound similar to holding a card in the spokes of a bike, then you have a leak. If not, then I have no idea what the problem is. I wouldn't change the EGR unless you knew it is the EGR.

So you replaced the intake gaskets? Was that the original diagnosis by the mechanic?

Anyone else have ideas?