94 Suburban K1500 wont start

My truck isnt starting, we have replaced the map sensor, cap and rotor, and ended up doing the distributor as well, plugs and wires, ignition switch. Should we re stab the distributor at tdc to make sure it is where it should be spark 1, like I said it is just flooding the motor at the turn of the key at start up, the temp sensor has been tested and shows it is funtioning, replaced injectors and still dumping fuel. The mechanic says ecm, got a new one same thing got a new one with a prom samething, only code is OBD1 Electronic spark timing. It will fire up if you hold the thottle down and shut fuel off at startup but idles rough like it is out of time, it is at 0