Did you check the vacuum hose? Have you run any of the EGR test modes? I think I've only ever seen 1 person claim a pressure converter solved the problem (but it was a complete activation failure, and the code said as much). Yes, the EGR pressure converter is on the opposite site of the engine, way in the back, tucked under the intake. You don't need to mess with it since there are connections you can hook into. I fixed mine with $10 of rubber vacuum hose and plastic connectors. Rerouted around the engine so it doesn't rub/get hot.I'm chasing the same Issue..
I'm assuming the OP got this resolved at this point..
But I believe that the pressure converter is actually under the Intake Manifold, if I understand some other posts correctly..
I used a throttle return spring from Autozone. Tie wrapped it to the body for tension adjustment; it doesn't need much tension btw. The other end just hooks over the ball mount for the vacuum cylinder actuator arm. Mine is an interim fix too, but for a different reason. I can't wait to do a full delete and get rid of the 3 troublesome systems: EGR, DPF, SCR a little later this year!...I just used a hardware store linear spring hooked to the chassis to fix it for now.