If there is a fuel filter under the truck I would suspect that the fuel tank has allot of crud in it which is why the filter is there before clogging the main firewall filter.
After reading your symptoms the fuel filter is my first go to for the symptoms you described. As the truck is in motion the filter gets saturated with crud. After the truck is off some of the crud will fall from filter and will let some fuel pass until it clogs up fully again. As truck loses power blue smoke begins to get more dense.
The clear hose on the return line is a great indicator of air entering the system but does not tell you where from, and that is reason enough to begin to replace all rubber fuel line. As Barrman suggested replacing simple filters and fluids by you will give you a baseline to begin from.
Keep a journal of all maintenance and repairs that you do from now on, day year and mileage of repair. I do this for my own equipment so not to rely on memory for answering questions that I can refer to a ledger for answers.
I would drop the fuel tank and clean it out to make sure you do not have to continue with filter problems, or keep an extra filter for under truck and will be a miserable experience changing on the road.
I have 2 spin on fuel filters for my diesel trucks, 1 5 micron and 1 1 micron and if the tank is contaminated usually the 5 takes the brunt but eventually the one gets dirty also. But for time and money dropping the tank is the best maintenance you can do. The least amount of rubber in the fuel system the better. Replace all rubber fuel lines and clamps, and get the short hose at the cab to frame junction behind the fender well tub. The hose is the least accessible and always forgot about, and always creates havoc at the worst time.
Good Luck and Detroit's are the best.