Transmission Problem? Maybe?

[mike300]

Hi guys...First off wanted to thank all the people who post on this forum, I am longer time reader but rarely post. I have a 2006 4.4i that I purchased 2 years ago. Ever since I bought I have noticed an issue. In 6th gear, 1500 rpm, at approx. 60kms/hr it feels like something is slipping. The best way to describe it is riding a bike on the sidewalk and every second of so, it feels like I am going over a crack. Almost like a thud that you can feel but you can’t really hear. The instant this happens the fuel economy gauge goes forward about 1/6th and then back down. I took it to the dealer and the shop foreman came with me for a test drive, but I could not reproduce it because the roads are bad and we couldn’t notice it. He says he cannot do anything about the issue until he experiences it first-hand. The issue occurs every time at this speed and gear. The shop foreman who was with me told me has never heard of the issue I describe. Is this a transmission thing? Should I be worried? I know there are dozens of transmission threads on here and I have read most of them. I have warranty for the next year so I want to get to the bottom of this ASAP. Thank you in advance everyone.