I have posted on this a couple times, each time i get new things to try, but none of them have worked yet.
Basically, jumping on the gas from 0% throttle produces a stumble in the engine, usually when the rpm is between 2000 and 2800. It also starts hard occiasionally. Seems to be getting worse.

Here is a list of things that have been replaced:
PCV valve
TPS
MAF
Fuel Filter
Spark Plugs (NGK coppers)
Fuel pressure regulator
Cleaned TB
new fuel pump (walbro 255lph)


throws no codes. had them checked at autozone.

Will coilpacks throw codes?
Could it be an EGR problem?
How about an IACV problem?
Could it be a knock sensor?

I am running out of ideas here.

here are videos with sound, you can hear the problem.
http://www.eng.buffalo.edu/~ctnewman/MVI_0008.AVI
http://www.eng.buffalo.edu/~ctnewman/MVI_0134.AVI

these are poor quality, and its hard to tell how bad it is, sometimes the car will shudder for like 2 seconds.

I am thinking about just taking the car to a dealer, but i dont want them to charge me a ****load of money and then just wave it off as "it is because you have a turbo"...

The only time it does this is when im not boosting, runs great oon boost.

To entirely rule out turbo problems, could i drive my car without an air filter for a couple minutes, by just disconnecting the piping before the MAF.

I am at a loss.

Well, i just readjusted my TPS and cleaned my IACV.
Haven't tested it yet.

Does the EGR work in both open and closed loop modes? Or just one.
Will a bad coilpack always throw a code?

-ctn