[Twix]

Loose ground for the radio causing interference? I used to get a whirring sound in my old Chevette when accelerating but it would go away at idle. Checked my radio ground (since the noise was coming through the speakers) and the problem went away.

It's nearly impossible to diagnose your problem without having the car to look at in person. But to give the dealer an ultimatum at this point is kind of crass. Good luck getting them to lemon law the car this late in the game.