Odd TDI problems - please help

I just purchased a 2006 jetta tdi with 194k. I was told it had a bad camshaft when i purchased it, and naturally i got it cheap.

It had the vacuum line going to valve cover (vacuum reservoir i do believe) disconnected, and the previous owner told me it runs better with it off. upon reconnecting it, it wouldnt even take throttle.

I purchased a n75 valve, cheap ebay special, but new none the less. figured id give it a try as i had problem with one on a 2.7t audi i used to have. no difference.

With the vacuum line disconnected the car ran, no boost, slow, but driveable.

I purchased a camshaft and lifter kit, it came with gaskets, bolts, water pump idler, tensioner, timing belt. it was an AMC cam/lifter kit. the old camshaft was mildly worn, semi sharp edges on a few lobes, but no completely destroyed lobes or lifters. I replaced the camshaft and lifters, and even though the belt and pulleys looked almost new i changed them, i dont want to worry about anything for a long while. I also changed oil and filter (napa gold and liqui-moly 5-40 syn diesel oil speced for vw 505.01?) and a napa gold fuel filter and air filter. I also adjusted the fuel injectors (bottom out then back off 180 when lobe is in proper position)

after putting the car together, it ran perfect like a brand new one.. for a couple hundred miles. back to THE SAME problem.

more detail of the initial problem. with vacuum line disconnected, runs fine with no boost. vacuum line connected i can push pedal to the floor it wont move, for 15 or 20 seconds, slowly rev, dump tons of smoke then take off, once or twice. then it goes in limp mode and quits boosting. at that time it does the same, but doesnt take off fast cause of no boost. during all of this the engine will rattle real bad as its taking off. i dont have vag-com, but i have a snap on modis ultra. i got a few codes without the engine light on. this is with vacuum line connected.

00564 (p0234) boost presssure regulation limit exceeded (overboost condition)
00305 (p0131) o2 sensor b1s1 signal low - intermittent
00257 (p0101) Mass air flow sensor (g70) implausible signal

i have randomly got a 01027 egr malfunction.

things i have tried since:
disconnect MAF - no change except maf circuit code
cleaned egr valve - had some crust. kinda cleaned it (ran out of carb cleaner)
visually inspected camshaft. didnt appear to have any damage
dont appear to have boost leak (can verify with smoke machine if i need to)

can a MAF cause all of this?

has anyone ran into similar problem? Im an experienced mechanic, i have worked on my fair share of vw/audis (and other euro cars) I rebuild automatic transmissions, and have lots of diesel experience (mainly powerstroke and cummins) this is my first vw diesel. if it was a powerstroke i could answer any question about it!

ive done lots of searching. cannot find a similar problem. what bothers me is it ran PERFECT after cam change and now same problem. if someone can point me in the right direction, or suggest anymore tests i have the tools and skills to do it. my scanner shows all the data.

Thanks for reading and helping me! -Russ

Sounds like a vacuum issue to me

Some specifics are missing here. First, when you say the vacuum line to the reservoir is disconnected, how is it disconnected? Do you mean it is just pulled off and laying there, leaking air back into the vacuum pump's attempt to create a vacuum, or is the hose plugged? Second, have you checked all of the vacuum hose connections, hose conditions and vacuum component functionality? I had a vacuum reservoir that leaked that caused problems for years before I finally figured it out. The glue seam had cracked. I also had a cracked plastic hose that went to the brake assist where the crack was very hard to see. Also, are the hoses all connected in the correct place? It is easy to connect them wrong. Here is an easier to read vacuum diagram I created to help me figure things out.

line pulled off creating vacuum leak. all the lines up top to n75 valve, valve cover etc are correct, i didnt verify on the egr and bypass flap. being that the problem was fixed and resurfaced is what leads me to believe either maf or egr. as no lines were changed before or after the camshaft change. or since the problem resurfaced.

Early on, I realized that these cars are wonderfully complex, which is not necessarily a good thing. Since VW does not publicize the logic of the ECM, we have to guess what the ECU will do when sensor or mechanical failures occur.

Shortly after buying the car, I obtained a VCDS, as I had concluded that I could not continue to own it satisfactorily without one. The way I remember it, it can generate 14,000 measurements, which are far too many for me to understand. I recommend that you do the same, which is to obtain a VCDS, use it and analyze the measurements it can provide. Once you do that, I look forward to seeing the combination of your extensive diesel experience in this forum, as with the information it provides, I believe you will be able to solve the problem quickly.

Fixed!

after having the problem become worse after i "cleaned" the EGR valve i took an educated guess and ordered one. $65 later for a chinese one off of ebay car is fixed and runs great!