I have a 2006 6.0L 250 Super Duty. Ran like a champ until lately, just under 89k miles on it. When it starts, especially on cool mornings (mid 50s is the coolest so far), it won't shift out of lower gears until high RPMs, and it seems to be running rough at those higher RPMs too. By the time i've driven a few miles, all is fine, and she's good the rest of the day. Any ideas? Thanks!