1992 Chevy Silverado 1500 5.7L V8 4WD Mileage 116,000

Yesterday I had problems starting my truck. It usually starts right away but I had to pump the gas to get it to start. After driving for only a few minutes it starts to spit and sputter. It was trying to stay running but it cut off after it made a few "clunking" noises. After it shut off it has not cranked up since then. I check all fuel lines and fuel pumps and gas is making it into the carburator. I checked the spark plugs, and they were firing. I replaced the distributor cap and rotor button, but it did not help. I also replaced the pick up module but it didn't help either. I checked the timing twice by removing to different spark plugs and moving the cylinder to TDC and checking the rotor button and it was aligned with the correct wire both times. I also felt the compression with my finger as the truck was being turned over and air was pumping out. (I'm not sure how hard it should be.) The truck still just turns over and doesn't start. I sprayed starter fluid in the carburator and still couldn't get the truck to run. The spark plugs were sparking and gas is making it into the carburator but I can not get it to fire. Is there anything else I could check? Any idea on what the problem may be? Any help at all would be greatly appreciated. Thank you!