there could be a couple different things causing it. you could possibly have a clogged up fuel filter, or you might just need a good tune up done to it, spark plugs, wires, distributor cap and rotor.
First check the PCV valve, shake it and if it does not rattle freely then replace it and your problem may be solved. If problem remains then try changing to a higher octane fuel this usually takes two tanks to feel a difference. The next step is to change to high quality platinum spark plugs and new wires
