Originally Posted by MHunter
Mine had also had the plugs and wires replaced recently by the previous owner but they used budget Autolite wires and Champion plugs. I replaced the wires first with OEM AC delco wires and that took care of the misfire 100 percent. Then I replaced the plugs anyway since I already bought them. I used AC delco plugs as well.
This was going to be my exact advise, for the same reasons. You may not know what brand/model of plugs and wires the previous owner used. Misfires (which is what your car sounds like it'* doing) are usually caused by plugs, wires, or ignition coils. GM cars seem to like ACDelco the best, which usually falls in the middle of the pack price-wise. I believe many ACDelco ignition parts were made by NGK, so those would probably be fine to use too.
Check Rock Auto, and also parts store websites like Advance Auto and Auto Zone for any promotions you can use (they often run 10-20% off deals)... order online and pick up in store, best of both worlds because you can save on shipping and return to the store if you have any problems. Rock Auto always has 5% off codes floating around, which will at least pay for most of your sales tax. Retailmenot.com also is a GREAT website for finding current coupon codes for almost any website store that you can imagine.