I have an '03 6.0L that I just finished doing some routine maintenance to (Oil, fuel filters, etc.)
First problem: I took the EGR valve off to clean and reinstall, but the bottom half of the valve broke off and was stuck in the engine. By stuck, I mean the packings/soot was holding it in place and I had nothing to grab onto since the top half was completely unattached. Long story short, I got the piece out, bought a new EGR valve, cleaned as much soot as I could and stuck it on there. Hooked everything back up and went on a test drive.
Side note: The soot on the old EGR was more-oily-er than normal.
Real problem: The first minute of the truck running is fine, but then there is a "louder-than-normal" knocking noise and an obvious sound of struggle with a short burst of dark smoke out the exhaust, then clear. While driving there is rough idle, short loss of power, and sometimes like I am getting too much power, and then eventually stalling. Bully Dog tuner gives me a code of P0403 EGR Control Circuit. There is nothing else unusual, no leaks or missing fluids or anything. I did try running it with the EGR valve electrical connector unplugged and it made no difference.
I need any and all advice, honestly. Taking it to a diesel shop tomorrow. Like any average vehicle operator, I want to find the problem and fix it, I don't want to throw a bunch of money at it unless I have to. I have considered deleting it, in hopes of fixing the problem. Mechanic said it'd be about $700, which is fine IF it fixes that issue, but not if there is going to be more repairs following.