Its was Fords Band-aid fix for a piss poor fuel system design...
#8 is at the end of a dead head fuel system, any air in the system gets trapped there, and is forced out #8 at some point. #6 and #8 fire right in line, #6 first then #8... #8 gets starved for fuel so some people in the early 99's complained of knock... Ford came up with the AE injector which has a long lead first shot...