If all the new rubber lines you put in are "fuel hose" and not generic rubber hose I would contact the vendor / manufacturer about a possible defective product. The only other thing I can think of is you bought gas that was contaminated with whatever the "coffee grind" crap is.
Are any of the rubber lines in the fuel system original or is everything new? Did you install all new hard lines or are those original to the truck also? If the "coffee grounds" are black then it is probably bits of deteriorated hose.
While you have the tank out install a new OEM replacement if you want an easy fix. Or have the old one boiled out and sealed if there are any places in your area that provide that service. There are DIY kits from Eastwood and POR15 to seal and clean old tanks also.
I have been following your thread for awhile and am really sorry to read about your engine. Another vote that the machine shop should make it right at no cost to you.