I have a 2000 Villager- rough idle, throwing misfire code on cylinder 3- had diagnosed, injector #3 not firing at all. I replaced #4 injector last summer- with this latest failed injector, do I replace all 3 injectors on the back bank while #3 is being replaced? I understand this is not common for injectors to fail. Just trying to figure out if replacing all 3 would be necessary or if I can save some extra cost. Will also perform fuel system/injector treatment and replace fuel filter.