Hey folks, I finished an receint service check at 100k and soon after, I felt a weird vibration and what feels like a misfiring at around 2500 rpm and up. This feeling is normaly felt on the highway around 75 mph or higher.

During the service check, I installed all oem parts including (FR7KTC) Bosch plugs, fuel and air filter, trans, coolant, and brake fliud flush (done by shop). Once I installed the new plugs, I noticed a differnt feeling at power up. I believe the plugs were gaped correctly.

I must add, that there is a slight squeeking noise noticed at idle (sounds a little bit like a diesel with the windows closed) which I feel, may be a idler pully. I inspected all pully's but found no play; however, its sounds like it is next to the supercharger and the only visual problem, is the fan blade has some play around the connecting nut.

I will remove the plugs and see if that takes care of the problem, but I feel that is not going to help. Any suggestions?

SIDE NOTE: I just reinstalled the old plugs and the engine is much smoother, but I still have the noise from the pullys.