I have a 99 ford taurus first starting up an driving it it runs good little skip to it but not bad jump an drive off does fine but no matter hot or cold after bout 20/30 mins of driving it losses ALL power skips HORRIBLE runs like its out of gas an smokes like a freight train smoke changes from blue to white then grey then back to blue but always smells the same ( like its running EXTREMELY rich but if I shift to neutral while driving an shut it off an immediately start it back it'll run like nothing was ever for another 20/30 mins then starts acting up again ..... SUGGESTIONS? ??? I have replaced coil pack, plugs, wires, fuel pump, filter, EGR, and MAP sensorstill no change but I happened to notice back middle injector is making a loud tapping noise an front left plug keeps fluding with fuel every time I pull that plug its soaked in gas.... please help?????

SOURCE: 96 ford taurus

Had the same problem with a Ford Ranger 4 cylinder. It turned out being a blown head gasket between 3rd and 4th cylinder. Compression was blowing from one cylinder to the other. Some times it ran great then others it couldn't pull it's self.

SOURCE: Ford Taurus choking at 4000rpm

maybe your EGR valve

SOURCE: 2000 TDI - Lots of white smoke at cold start.

Sounds like your injection pump timing is off, an injector is leaking or a bad seal on your IP.
VW dealers have a horrible reputation when it comes to TDI's. Check out the posts over at www.tdiclub.com Those guys are very knowledgeable - and the first thing they'll tell you is don't take it to a dealer.
You can probably find someone in your area that has a copy of Vag-Com (scantool software that vw uses) software that could look at your timing. It definitely sounds like your dealer was throwing parts at your car because they didn't know what your problem is. If I were you, I'd copy and paste your post from here over at www.tdiclub.com

SOURCE: 2002 ford ranger 2.3L skipping at idle. Replaced plugs, plug wires, coil and cam sensor. Need help. Whats next fuel injectors?

Repair Shop--- you installed too many parts already,
on a guess with no testing