1992 Chevy S-10 wont start

Hello, my truck wont start. It has fuel, it has spark but no fire. When truck last ran it die out and had no spark. Has new plugs, wires, cap, rotor, pick up coil, ingition coil, ingition distributor on distributor. While trying to turn engine over it will hydrolock because of fuel not being burnt off, then needs to be tow to bump start to free engine(with plugs out and belt off). Engine is a throtle body injection, fuel pump is fine, fuel regulators on throtle body are fine, my brother's been workking on this for over a week. Truck has been hooked up to a code reader and no problems there. Vechile will back fire from time to time. Please help the two of us are lost in the dark on this one.

thanks your time is greatly apprecated