Sounds like the carrier bearing. Mine did the same. Quick and inexpensive fix.Not exactly sure where this fits, so apologies if it needs to get put in a different forum topic. I've been dealing with something on my GT that's been driving me nuts for well over a year. Basically it's that if I start from a stop and give it enough gas (doesn't need to be floored), it sounds/feels like I have a stuttering sound coming from the rear of the car. I can feel it under my seat as well. It's not a clunk like suspension, but more of a repetitive sound (similar to the rhythm of a woodpecker...like 4-5 thuds per second). The more throttle you give it, the louder and more pronounced it is. I've had it diagnosed numerous times and they can never find anything. I've had my struts replaced, bushings, axle seals, etc, which is why I don't think it's suspension. It stutters too quickly to be related to the wheel turning as the wheel isn't rotating that quickly from a stop, so I'm thinking it's more like a gear/cog slipping somewhere, something related to RPM rather than wheel rotation. If you roll into the acceleration it doesn't do it, nor does it do it if you hammer the gas while driving (I get a periodic power drop/surge when floored, but I think that's something different). I can sort of get it to do it in a second gear start, but primarily it only does it on a first gear start from a stop. After you accelerate enough, it'll just fade out and stop doing it all on its own. Drive/sport/manual shift doesn't matter. Does it with both my summer and winter wheel/tire combos. Could it be something like the ABS or some other traction control thing kicking in to limit wheel spin when it's not needed? I turned off the stability control and it still did it. Appreciate any thoughts that I can take back into my mechanic to look at.