93 s-10 won't start intermittently

93 s-10 4.3L TBI, idles rough(loping)when warm and sometimes won't start. It turns over just fine. If I pour a bit of gas into the intake it starts and runs. It always starts cold but is intermittent when warm. I noticed that the injectors aren't firing while trying to start it when it won't start. No adverse performance while driving. When it is idling rough it smooths out if I unplug the idle-air control valve but having this unplugged doesn't change it's ability to start.
Has new plugs, wires, coil (6 months ago). new fuel pump and filters. new idle-air control valve(seems to have helped but this might be a fluke. I haven't been able to check the codes but i'm not getting any error lights on the dash.
Any advice would be greatly appreciated. cheers

Andrew

When no start check for lose of fuel pressure and spark and injector pulse.
Any check engine lights on or codes set?