2003 A4 1.8t Quattro Avant, 105k miles.....REALLY well maintained!

So, I got the SpeedTuning ECU in, and within a few miles of driving I got the p0299. (no codes at all before speedtuning)

So, based on that, there was a natural progression of events. I ordered a boost leak tester, and while I waited for that, I went ahead and replaced the diverter valve with the newer version from the dealer, and I also replaced the PCV valve, and bypassed the n249.

Code still came back. Car seemed to be boosting okay, but did lose boost and seemed a little inconsistent.

So, I got the boost leak tester in yesterday, and did the test today. It wouldn't hold past about 12psi!

suction jet pump was leaking, so I replaced that with the new version from the dealer. I had a few tight, but loose clamps on boost hoses and the diverter, so I tightened those up.

After all of this, NO BOOST LEAKS!! I was holding about 25psi of boost, and I figured I didn't need to push it much more than that.

Put everything back together, cleared codes, took it for a ride and it does seem alot better, but still getting some inconsistent boost.

And there was that SOB p0299 again.

Now I'm lost. I've done everything. temp boost gauge shows I am boosting up to about 19psi and then holding at about 17psi...and it does jump around a bit with gear changes.

Any ideas here would be alot of help!!! I feel like I've done everything possible. Turbo seems to spool fine also!!

N75?