I have a 96 Pathfinder with 105K miles on it. I noticed my valve cover gaskets were leaking so I decided to change the gaskets and do a tune up on it (plugs, wires, distributor cap, and rotor button). As soon as I got my Pathy back, I noticed a slight miss below 3000RPM and a lack of low end power. The longer I drive it the worse the miss gets. Any ideas??