Hey guys, I have this issue that's driving me nuts with my 2006 5AT. Ive noticed an intermittent shaking/shuddering under slight acceleration around 2200 RPM and again around 2900-3000RPM. The engine/trans will shake hard for a second or two and then go away as revs increase. It's definitely not a wheel balance issue because it reacts purely to throttle position. My car is just shy of 80K miles but this has been going on for several months and I really want to figure out why. The trans and rear diff were serviced around 66K. Still on the original spark plugs. I read another thread of people reporting similar issues but they were happening for them around 40mph...mine are above 60mph and always when the car is in 5th gear in auto mode. Is it a drive-by-wire throttle issue?

 

Sounds like you have a good grasp on how your car runs. Before anything, check the simple things. I had a similar problem (at certain speeds) and it ended up being two loose lugnuts. The other time I had a bad sound it was from chitty tires up front. Good luck and let us know what it was!