Even more so if it will start when you floor it. That is exactly what is done on EFI's to overcome a no-start flooded condition. When you floor it, the EEC senses open throttle, and will not fire the injectors when starting.The truck will start up fine when cold, rev up when not in gear...once it goes into gear, no power.... and once it stalls, you have to put the pedal to the floor for it to start.
Still a fuel problem?
Try this on your cold engine. Push the throttle to the floor, and try to start it. If it starts, go get a fuel pressure regulator. If the engine starts at WOT, that means you have fuel going in when you shouldn't. It's a good injector test as well, if you know the FPR is good. There's only two ways fuel can get to those cylinders. The right way, through the injectors when fired. The wrong way (any other route or reason)
If you want to go buy a timing chain, cam gear, and crank gear, be my guest. But, I think you'll be wasting your money, and signing up for a whole lotta labor that's very subject to introducing a whole new set of problems.
Black smoke, no power, back-firing is all symptoms of a failed FPR. It takes about 30 minutes to change the FPR, and IIRC, I paid about $15 for mine.