I'm a little puzzled by your comment : "not that good of vaccum from intake manifold". Manifold vacuum is created when the pistons travel downward in their bores. If you have low mainfold vacuum, then you either have a major vacuum leak somewhere (brake vacum booster comes to mind), or possibly valve/timing problems.
My advice is to open the hood, and listen. Listen for the sound of the engine sucking air. The only place you should hear it coming from is the intake of the throttle body. Feel around. Start tracing all the vacuum hoses coming off the intake mainfold. Inspect them carefully. Small cracks can lead to big leaks.
Just re-read your original post. Changing the fuel pump souldn't have anything to do with it, unless... You did change your fuel filter after changing the pump didn't you? If not, do it. You may be starving for fuel if it's partially clogged. Who knows what kind of gunk you may have dislodged after pulling the fuel pump lines.
Post more when you check it out a little more closely.
