I used to work at a small time garage and when people would come in with problems like this we would usually laugh behind their backs but I know its not in my mind
Starting about 9 months ago, one day the truck hangs up in first and wont shift out till abnormal RPMS......I'm headed home and I pull into a gas station, noticing I may be too low on gas to get there. Fill up, panicking about my tranny going start to head home....No Shift problems. Thinking I "Dodged" a bullet.
2 or 3 weeks go by, Shift problem happens again....I'm bummed, trying to rev it high to shift, looking a the gas I notice its, low? Could it be coincidence....Fill up....Fixed. 3-4 more times this happens...Baffled but I use my truck a lot for work so I don't have it checked. Just keep the gas filled up.....
Couple weeks later it returns but not just when low on gas now....Finally throws a code, Get it scanned, speed sensor. So I replace it. Runs fine for a week or two.....Starts missing second sometimes. Another Code, Gets worse and worse, So I take it to local Goodyear, They say it needs a $3000 rebuilt Tranny.
Just doesn't feel that way to me. For a long time it would run fine for a week. Or a day, then mess up here and there. Now, I run it in low, manually torque it up and shift, it to drive. Gets me by, but lately it seems like less and less power, Can hardly pull a trailer up a slight incline.
On another but maybe related note, seemed like either a high pitched rattle or possible ping from the engine under heavy stress for the past couple years, but If I ran High Octane it would go away, now no matter what it comes on at relatively low exertion now.