The car is a 1993 Chevrolet Caprice 5.0 TBI

I recently changed the intake manifold gasket, valve cover seals, thermostat and the ETS, and fuel filter... after replacing all this I cannot get the car to start after sitting for periods of time, it will start after being warmed up. I have checked distributor timing, all electric connectors, vacuums, cleaned the injectors, etc. I dont think its fuel related because the car runs GREAT after you get it started, no struggles and I recently drove the car over 1,000 miles with no problems but am stumped on what to do next. ANY advice would help!