What could be wrong when it sputters?

I have a 1984 chevy blazer full size. When I first start my truck in the day and I push the gas it like bogs down and sometimes stalls. After I get it running for a bit when I got to accelerate it has a little pause then it takes off. I have changed the somethings. I put in a open air filter and took out the old one. I put a brand new rotor cap and distributer in it. I was going to put a new fuel filter in it but for some reason I can not find where it its at. I know it is a inline filter and is located on the frame on the left when facing the front of the truck. I run my hands along with the fuel lines but can't find one any where. What else could be the problem with this loss of power?