Everyone’s inputs troubleshoots and ideas have pretty much taught me a lot of my “COLD BLOODED BEAST!!!” ~ 04 5.9 Cummins 3500 4x4. With only 140k miles. All highway. It sat for nearly 6 years as you can tell it’s barley breaking in. Iv been having similar issues and worse. Wanna share and ask for ideas and inputs also possible fixes and or stories as mine but with happy ending. , It’s been 2 winters that I notice once it starts getting cold ( California cold) 40 degrees she acts up. Riding fine at take off for a one ton before catching last gear rpms go up high as 3500-4500 , Throttle pressure has 3/4 play and I start to decrease in speed even though I repump gas pedal and it catch that last gear but drop it and again rpms up so on and so forth. The first winter it did that I was about to bully dog tune her but notice that and withheld. Took her to my mechanic whom rather sleep in his Cummins than his wife, changed the trans to a new one with stage 2 upgrade. Spring came along and the 35 and me were like...