Hi I just recently purchased a 2004 srx v8 northstar with about 174xxx miles on it . The problem happens intermittently, for no known reason the car suddenly shudders and kinda tracts left a bit like I just ran over some washboards on a dirt road. The radio flashes a traction system engaged message and then goes away. I tried to make it do it by releasing the gas or hitting bumps on the road but it will just randomly due it. Any advice will be appreciated thank u.