My car shakes a little. .. But only at normal opperating temprature. Why

I'm a little confused on the problem, by rumble do you mean a sound? Or is the car physically shaking? I only ask because if is physically shaking it could have something to do with your fuel injectors or with your timing belt.

Fuel injectors have had 4 bottles of seafoam go through them, seafoam in the oil, seafoam in the air intake,.... It sparkles in there The rumble is a mild car shake that can be felt by the passangers of the car, but if you were to place yoyr hand on the car or engine it is very hard to distinguish from the regular car vibrations... What else can i tell you about it... To narrow this down

Hey Tox- you ever figure out the problem and get it fixed? My 05 CTS is doing this at stop lights and low low speed only. Fairly rough shimmy that feels like rear of car. Gotten progressively worse. Would love to know what you figured out because I still owe money on this car I love but also hate. Don't know what to do at 120K miles. Please if you learned anything, price estimate , ideas, I'd love to hear them. See that someone else answered fuel injector or timing belt-email me at saywhatiknow@gmail.com

Only about 3 days ago out of boredom, i went to canadian tire and picked up some belt dressing, and i was screwing around with my brothers car and then thought to myself that i should do it to my car while im at it... As i found out my car stopped the mild shake and i now know that i need my belts done and or any or all the belt wheel and connecting parts checked out for an odd ballance issue... Spray your belt to see