I know that plugs, plug wires, EGR (check engine light is on, and that is what Auto Zones computer says it is)......what else is involved? Is there a standard old type dist cap and button? What else do I need to to a tune up. My gas mileage has dropped out the bottom and i think this may help

 

plugs, wires, fuel filter, and pcv valve thats a basic tune up. no distributor or rotor to change.

i would be more suspisious of the DPFE sensor than the egr valve. seems like auto zone always says replace egr valve but dpfe, plugged egr ports in lower intake manifold, faulty wiring, disconnected vacuum hoses. all these can cause code P0401 and P0402 which is most likely the code they read if they said egr valve. but i would almost bet its a bad DPFE.