[jeff2465]

I also had similar symptoms, but it ended being the serpentine belt. I first tried the jack (with wood block) under the oil pan test to see if the vibration stopped after taking some of the engine weight on the jack. No change in the vibration. Although the existing belt looked good, it had stretched and it was not loading the tensioner. The tensioner made a loud racket at idle, and especially when placed into drive. After pulling away the coolant tank, you could see the tensioner rattling. New belt quieted every thing down.