Hoping someone out there has seen this one. I have 28K on a 2011 6.7L Lariat. While accelerating normally (every day driving with no trailer or additional weght on truck), when in 3rd gear the RPMs increase as expected but then "decrease" a couple of 100 RPMs momentarily (see it on tach and hear it/feel it) and then increases again prior to shift into 4th. This only happens in 3rd gear. I have never seen this with a tranny before. It feels and sounds like this new tranny is "shifting" within the gear itself if that makes any sense. I had TSP 11-04-21 flash installed several months ago due to some hard shifting at lower gears and seemed to resolved problem. I have yet to take it in to dealer for this one because I wanted to research a bit before turning truck's fate over to service dept. Thanks.
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