Central Fi To Mfi Conversion Question

[pbellone]

I have a 98 K1500 5.7 109,000 miles with misfire issues. I have narrowed it down to possibly 1 or more bad fuel injectors and or bad O2 sensor(s). The problems are coming up mainly for cylinder 5 and a couple of times on 3. The lower intake manifold is a gooie black mess after pouring the TEC down it the fist attempt to fix the problems. I changed the cap, rotor, wires, plugs, fuel filter (never was changed) with all GM factory parts. I also just bought a fuel injector cleaner canister and ran it twice with GM TEC and gas. Fuel trims are different on both banks as well as the O2 voltages. So I will be changing the pre cat O2s first in my diagnositics before going for my lungs buying a whole injector setup. But...if I do buy the injector kit, do I stay with the central SFI or upgrade to the MFI?