White gunk in EGR tube, code P0401

[aleros_eat_rice]

My 99 GLS had the problem of white gunk in the egr tube, but a friend told me what was wrong. I replaced the egr and pcv valves, and the pcv boot. Over time, the gunk went away, but it still throws P0401.
What might the problem be?

[MMGT1]

Check the EGR tube to begin with. The 401 is insufficient flow DTC. If the tube is cracked it will throw the code your getting. Ive seen quite a few now that the metal tube has corroded or cracked through. If no crack, check wiring to the EGR, maybe a corroded/bad connection happening there on you
And that white stuff your seeing happens when a vehicle is not brought to full temp. Not getting the oil up to temp will allow moisture to stay in the system and that is the milky brown sludge that will result. Try to get it out and up to full temp at least a couple times a week if the car is subjected to short trips too often. A good half hour to 45 mins on the highway will do wonders to keep that issue at bay

[aleros_eat_rice]

I have a scanner, and I clear the code, it comes back on at random. I clear it now, it might come on in a few miles, or it might not come on for another day or two.
I did suspect the tube may be leaking. The connections are good with no corrosion, on the egr or the wire end.

What is a good place to get a replacement tube?
Edit: discontinued. I did find an egr line for a 2004 Alero that fits vin E motors, which mine is.

[aleros_eat_rice]

I may have fixed p0401. I asked one of my ex gf's (heavy equip. mechanic) why it would do this. She said to take a coathanger and poke around the hole on the plenum side of where the egr valve mounts. Said if it goes all the way, there is another problem, but if it doesn't go through all the way, its likely a carbon buildup, and just need to clean it and clear the code. I tried this, and you would not believe (or maybe you would) how much carbon was blocking it.
I cleaned it out, and I cleared the code. Hasn't come on yet, and I'm hoping it stays off.