Hmmm, maybe I've got the same problem with my Impala, an '02 LS (3.8L V-6). I do have a couple of troubleshooting questions though if you don't mind. First off, what mine does is like a real low audible rumble, almost the same noise as when your tires are out of balance and you're doing about 75mph only a little louder and always at the same pitch, meaning it doesn't matter what RPM's or speed I'm running, the noise is always the same. And it's a bad enough vibration to give double vision in the rear view mirror. Secondly, it feels like what you said about the transmission slipping slightly, but doing it a LOT. It stops when I let off the gas, and gets worse (louder) the more gas I apply. Also, it seems like it's worst before the car has a chance to warm up to operating temps. And lastly, it's getting worse over time*note*: it's been doing this gradually now for about a month.
At first I thought it was the tires because we had just had a new tire mounted because the previous one had a cut in the sidewall. I figured that they didn't balance it right, so I had them check it out and the tire was balanced perfectly. Then I got to thinking that it sounded like maybe a plug or plug wire or something in the fuel system wasn't working but a quick check didn't reveal anything out of the ordinary. So by this time I'm down to what appears to be my last option.....the tranny.....and I was PETRIFIED to find out how much a tranny for this car costs so I haven't found out yet. Then today as I'm getting ready to leave I decide to google my symptoms and here I am
This sounds almost exactly like the symptoms that my car is going through aside from the fact that I haven't had it hooked up to a scanner yet. I'm going to have it checked out and see what the damage is, surely it's not going to be as high as a transmission.... THANKS!!!
*EDIT*---Oh yeah almost forgot, about how much did the cat. cost you including parts and labor? just curious...thanks again
