Egr flow insufficient woes

Ok i got the dreaded p0401 code egr flow insufficient. Long story short over the last month i have replaced DPFE twice, egr valve, egr soleniod, sparyed the crap out of the intake and the egr tube with carb cleaner. Still everytime i have the code cleared it comes back within a day. Usually after the code comes on my car seems a little bit more sluggish. I took to a muffler shop and had cats checked out, no heat difference, they're good. I am pulling my hair out trying to get that light to go away. Anybody else been in this situation or have any suggestions? Thanks in advance,
Jon

no help anybody?