1996 k1500 wont start cold

I recently had to rebuild my motor due to oil pump failure. While it was out I put a mild cam (with recomended lifters), k&n intake, shorty headers, msd coil and wires. My problem is if I let it sit over night it wont start in the morning. I have to go out at 4hr intervals to start it and let it warm up in order for me to get to work in the morning. I dont know where to start looking for the problem. I have mild automotive experience but lacking in diagnostic part. A scanner only picked up a o2 bank2 sensor2 falt. It will crank till the battery goes dead. After it wont start when I get out I smell raw gas. So it kinda smells like its flooding out. PLEASE HELP! Im loosing lots of sleep and spending tons in gas to get back and forth to work.