why wont my kia optima not start

i replaced cat/manifold, crankshaft censor, exhaust side cam shaft censor, all
fuses in engine bay car will turn over but no fire sprayed fluid in intake not
getting spark or ecm not telling it to fire checked for loose wires and found
none bank 2 o2 censor was unplugged and there is a connector in bank 1 o2
censor harness but nothing to plug into it.i even put old converter and
manifold back on same thing it started and ran for couple seconds but now
no fire its not throwing any codes no check engine light on and it should with
bank 2 o2 unplugged it has 140000 miles on body engine was replaced its
key start non turbo 2.4 it was low on oil nothing on dipstick. i have tried
everything but replace relays.