Just finished up with same problem, thought it was sending unit and dropped the tank. Both lines separated where the flexable rubber joins the steel. I had a stumble and occasional miss at first when pulling out of the driveway. After a few weeks It ran like a big block with a cracked distributor cap. Changed the tank sender and rear lines, All Gone.
Found a couple of pinholes in the tank.
Dave
99 sub 2500, 326,000mi, 4:10, 265-75-16 rubber, remote Dtech fsd and turbo master from Heath Isspro pyrometer and boost gauge-Kennedy, 1.94 TDCO, 3" custom bent exh.
07 Suburban,08 LMM, Allison 6 speed.