When I come to a stop sign, or stop light sometimes my 6.0 will shift into/stay in 4th gear at a dead stop, it started happening on a fairly regular basis. I have 180k on the truck so I'm assuming that my tranny is starting to bite the dust, but I am wondering if there may be something simple that would be causing this?

I have cold air intake, straight pipe, and bullydog tuner.

 

Any codes? Have you maintained it with proper fluid? There is tsb on the recommended fluid and mercon lv is suitable for most applications especially in cold weather. There is a lot of information about the fluids in our trucks. I would look for a good trans shop, your problem may be easy fix if you don't keep pushing it.

 

Yeah it isn't throwing any codes and fluids are all fresh, taking it in tomorrow for a tranny

 

When you either start having trans issues with the typical powerstroke or just as a preventative measure, toss in a couple bottles of Lucas transmission treat, it does wonders in the ford transmissions. I was skeptical when I first heard about it and I watched my dad pour 2 bottles onto an 06 f-350 that wouldn't shift into reverse, and was having issues shifting out of first gear, he ran it thru the gears manually and it started reversing and shifting as if nothing happened. Now I'm a believer and user of Lucas.

 

If its staying in that gear I'd drop pan and inspect valve body for any valves that are hung up