This is what we can do to possibly fix 'Sliders'.
How about bringing back the original characters by saying everyone missed a slide at some point while their doubles slid and lived as them until they all met their individual dooms. Yeah, it's a bit cheesy and maybe even far-fetched, but given the nature of the show it IS possible. This could also allow room to say that's why the characters drifted apart. One could say they weren't sliding with their original selves for months and slowly their personality flaws became more prevalent. The producers would have to pick plausible points to say where Quinn, Wade, and Remmy missed slides and their doubles took over. I'm sure just about everyone knows where the professor's double started hitching a ride with the Sliders (the blue Golden Gate Bridge/Jets, not Dolphins world).
How they would script this show and set the plot, well I haven't figured that out yet...BUT the meat of the concept is there. Tell me this wouldn't work!!