Intermittent inability to start engine, initially thought to be in the ignition/key fitting

so the car has being doing this for a while now, it has been passing raw gasoline through the exhaust and smoke. I have changed the oxygen sensor, the fuel regulator, the spark plugs and wires, brand new distributor cap, fuel filter, and cleaned throttle body (with throttle body cleaner of course). I blame my father for putting the lucas fuel injection cleaner. The only guesses i have is that its the injectors or vacuum leak.

rear wheel bearing problems; how can you determine if they bad

My fuel gauge is not working, so I have to make sure I keep gas in my tank. Do anybody know how to repair this problem. Thanks in advance.