355 Steering Problem

I delivered a 99 355 Spider to a customer yesterday. I drove it about 150 miles. The customer went about 25 miles and said the car became almost uncontrollable and was wandering all over the place. Said there was also a noise coming from the engine compartment. From his description, it seems that the power steering was over powerful and the steering wheel was very loose. Power steering resevoir was full. Any ideas as to what would cause this? I'm thinking a bad sensor or something with the pump?

 

He had a 355 coupe. Plus, it was fine for 25 miles and then just happened. The tire/alignment can't change that much in 25 miles.

 

Thanks for the info. I will have those rear sub-frame bolts checked and will check the tire preasure and lug bolts.
A few years ago, I had a similar problem with a Porsche and it turned out to be a loose rear wheel bearing nut.
I will let you know if we find the problem.

 

Had the car taken to a shop during the week. They test drove it and of course it was fine. Went through the car top to bottom to make sure and could find nothing. They are going to bleed out the power steering fluid and replace the fluid to just make sure. Maybe it was just air in the line or kinked hose?
The car had sat for about three months prior to this. Have no idea for sure what happened.
Thanks for all your help and if you have any other comments, please post.