I have a 94 lexus gs 300 and I'm having some car trouble. When I crank my car up if I don't pull off as soon as I start it, it feels like it's going to cut off. When I'm driving down the road it shakes and rocks not bad but it's very noticeable. I also notice that when I go above 60mph it's shakes a little bit more. I had the spark pugs replaced hoping that would solve the problem it continues.

Any ideas what the issue may be?