Did you have your ignition module tested, I had a terrible time with mine my truck was exhibiting some of the same symptoms till I replaced my igniton module then it started right up.

 

when its running, does it make a sound out of the carb kinda like someone sucking on a straw in an almost empty glass(if you know what im saying), if it kinda sounds like that the carb is probably overflowing....on the passenger side of that holley on the side of the bowls, there should be 2 big round screws, one on the front bowl and one on the back, these are sight screws....take the front one out while its running, and if a bunch of gas pours out thats the problem, the fuel level should be level with the bottom of the screw hole, not pouring out......if its pouring out shut off the engine, look at the top of the carb on the front, there is a nut with a flat head screw on top of it, with a flat head screwdriver and a 5/8ths wrench in hand, loosen the screw just enough so you can turn the nut clockwise, turn the nut a full turn and tighten the screw....start the engine and see where the fuel line is, keep adjusting back and forth until the fuel line is at the bottom of the sight hole.....repeat for the back bowl too..you can do this with the engine running,BUT ITS VERY DANGEROUS AND IF YOU DONT TRUST YOUR SKILLS DO IT WITH THE ENGINE OFF!!!!...then get a timing light, unhook and plug the vacuum advance, get someone to keep the idle at about 650rpms, and time it to 12* BTDC.....if these two steps dont work you are in need of a timing chain to say the least....