Acura with a built-in Rumblestrip

My '04 Acura TL will fluctuate the RPMs when running at 1400, regardless of gear. It will jump back and forth between 1400 and 1600. When it jumps up, there is a shudder that feels like you are driving on a Rumblestrip. I have searched the internet boards and it seems a lot of others have experience the same thing. One of the posters said that Acura acknowledged the issue, but said they have no fix for it. What kind of horse hockey is that! I had my local guy hook it up to the dyno and found no issues. This thing is driving me crazy! You guys are my last hope. Please help me out before the doors fall off!

Chandler in the Outer Banks of NC