I have replaced the electronic ignition module the coil the fuel filter and fuel pump on my 90 chevy 1500 truck with a 350 tbi all within a year but for some reason it still only starts when it wants to. I have tried everything but it has a mind of its own. Does anyone have any more ideas?

Check the ignition switch for wear and pitting. Check all under dash and under hood fuses with a test light or multimeter. Remove and clean the contracts on under hood relays, particularly the fuel pump relay. Ensure you can hear the fuel pump run, when you turn the ignition switch to ON. Otherwise, I suspect the problem resides with the distributor. Either the Ignition Control Module is bad or there's a problem with the distributor itself (e.g. a bad pick-up). Always be sure to disconnect the negative battery cable when working on or around the electrical system.