This morning as my coffee was splashing out of my coffee cup in my 96 RAM SLT (5.2L), I realized how terrible my truck is riding and the amount of vibrations I am experencing. I do not feel the vibration in the steering wheel very much (if at all), but I can feel it in my seat and the passenger seat (with no one in it) is visibly vibrating. This use to be the smoothest riding vehicle in my driveway, now it's the worst and rides rough.
The seats also seemseems to vibrate while sitting still at red lights, but not as much. Based on that, can I rule out tires, suspension, shocks, etc?

What should I consider when looking for this vibration problem?

thanks for any replies.

 

shock resistant coffee cup