Code P0401 - Need help

[ColoBonne]

Have been getting the P0401 code intermittently for a couple weeks now.
If I'm really light on the gas from a stop the engine runs smoothly and no SES light.
If I drive normally or really step on it, it has no power, acts like it's missing, and the SES light blinks.
Soon as I let off and cruise, SES goes out and runs smoothly.
I put in a diff EGR valve from junk yard, same problem.
Removed the EGR mount and all the pipes are clear. No blockage.
Where do I go from here?