Jeep Grand Cherokee 2005 vibrates at high speed

What is your question?

I was test driving a Jeep Grand Cherokee Sports 2005 and it swerved to the right at 55m/hr and also vibrated too. The car has very wide tires and is 180K and wonder what could be the issue before I throw my money away of $2500. I checked the car history but shows minimum accidents, not savaged, and no major accidents except the recall. Theres some rattling noise from the air conditioner.Please help Pals!

What makes this problem better or worse?

when driving at 60 miles and over

How long has your 2005 Jeep Grand Cherokee had this problem?

for 3 weeks