They say that my ECU is modified.

I'm not sure hot to tell. I'm a novice but I'm willing to pull the ECU out where I can see and look at the chipset, it there is an easy way of identifying a non stock/modified ECU.

The dealer makes this claim...originally, when they were working on it there was NO claim of modification, no thee is!

The BPV has been replaced with their 710 N unit w/some assorted smaller hoses and the car still hick-ups, as you push the accel then lift then push and maintain WOT.

It's obvious if there is an aftermarket chip in there. AFAIK all tuners use some sort of socket, and if there isn't a socket, you can tell if the solder job was done on a wave machine or by hand.

There is no easy way to tell by VAG unless the car is running well so you can measure boost and mass air flow and compare to stock.

1995 S6 Avant

You usually introduce new scratches to the aluminum cover when you remove and reinstall the ECU. Some dealers will look at that as evidence that atleast the ECU has been removed at some time.

Take a look where the metal bracket holds the ECU down to see if there are any scratches. If there are, then that's an indication that it's been out and any new scratches won't matter. If it looks virgin with no scratches or blemishes, you may not want to remove it.

Since you've got an S6, I have no idea what the stock MAF rates or boost should be. You'll have to find someone else with an S6 that has taken such data. There are several of us around Atlanta with VAG tools that can help you out if you can get the stock #'s.

Kool! Not only that, they have been in it also.
But, it may come to that; this thing barely wants to run, when you come off the clutch and begin to accel. It puts and stumbles (3-4x) then all is fine until a hill and a little too high an gear.

ALREADY called the dealer (again) to claim, STILL NOT FIXED!

If he has a 1995 then his warrenty should be completely gone. So it shouldn't matter if he pulls his ECU out to check it, or that the ECU is modified unless that is the cause of the problem. Right? If the ECU is the problem then the simple answer for J. Ellis should be to replace the ECU and the problem should be solved. I would ask them if they think that is the problem or if they are just trying to tell you what might be wrong. Also, if they say the ECU is the problem ask them how they know.

Which J. Ellis did you bring it to?

If you want to know if the ECU has been modified. My suggestion would be to take the car to someone who knows what to look for (like RobC or a EuroTech) and just take a look at the ECU. Then you will know if it is modified or not.

When my friend had his Audi serviced in Greenville SC. they changed out the fuel pump relay and told him they fix his problem...well a week went by and the car died again...took it back and they found the real problem was the cam position sensor and they refunded him all the money they charged him for his previous repair...all he had to do was ask the manager.

My thoughts:

If there was another 95 S6 running around I would ask the owner to swap ECU's to see if it is the computer.

Some other items to check:
Fuel pump
Fuel filter
Bad cam position sensor...which screws up the timing.

Looking to get together with any like minded individuals to shot some scenarios, about what the issues could be....

lemme know - I can talk to them for you. there was not ecu mod for that model/year.