I got a 2009 V8 Vantage a year ago and for the past few months the car has felt very floaty when I accelerate hard on 1st or 2nd. The front and back go all over the place especially if accelerate hard during a lane change on 1st and 2nd. It has to be the tires right? My dealer just checked them and said they are fine. They are the original tires that came with the car (it only has 7k miles on it).

 

Check right rear control link bushings

 

Did you have this issue before? I have no idea how to check that. I guess I will drive up to my local dealer again soon.

 

Those tyres are 4 years old and @ 7k miles probably hitting the point where the RE050's drop off.
Also I doubt your car has ever had a 4 wheel geometry set up
Are the tyre pressures the same on the rear axle?

 

It could be something as simple as over-inflation.

 

I agree! Check your tire pressures first.

 

I just had it serviced a week ago. They checked the tire pressure already. I did some more research and I think its the bushings. My steering wheel also tends to shake a bit at high speed on the highway. I am going to bring it in soon for a check of the bushings.

 

If they are going to check the bushes get the 4 wheel geometry checked (and adjusted as necessary)

 

But did you check the tire pressures? I ask because I've found that dealers are often very poor at getting tire pressures correct (my Aston dealer is perhaps the only dealer who hasn't gotten them very wrong). I have checked pressures immediately before leaving a car with a dealer for service -- when I pick it up after the dealer "adjusted" the pressures, they're almost always wrong...

 

Could also be an alignment issue...toe especially.