I was wondering if anyone could help me diagnose a problem with my 2004 F-350, 6.0L FX4, SRW. Here is the problem. When the truck is cold and it is cold outside (< 60 degrees or so) I don't really see this problem, but when the truck has warmed up and the outside temperature is warmer the problem begins. The warmer it is outside, the problem is more pronounced. I have driven in the mountains for 6 hours straight recently and the problem stayed very mild (it was very cold out), but I can drive a short distance when it is hot outside and it becomes very noticeable very quick. The best I can describe it is as "drivetrain slack". When I am coming to a complete stop it feels like I get a little bump from behind, almost like pulling a trailer with a pintle hitch. Then, when I take off from a dead stop, I will get rolling and at after a couple of miles per hour and about 10 feet of roll or so, it feels like something catches up and I feel a little jerk, again like a pintle hitch getting tension or something in the bed rolling to the back of the truck. I have tried holding the brake just a little to see if I could take up the slack before I get rolling, I have tried taking off holding the auto transmission down in 1st gear and with the tow/haul engaged and nothing makes any difference. Any ideas or other things that I could try to solve this would be appreciated.