#5 cylinder misfires

I have a 2000 Chevy s10 zr2 extended cab, back in
September it started misfiring on #5 cylinder, not
all the time but is sporadic, I changed the plugs,
wires, cap and rotor, it still misfires, finally I
replaced the spider fuel injectors but its still
saying #5 cylinder is misfiring, one day it will be
running fine seemingly and the next day it runs like
crap, fuel smells rich, I also notice sometimes
when I first start it the tach will jump up a few
times or sometimes I'll have to crank it a few times
before it starts, any solutions? Thanks