I have a '95 Lumina sedan with a 3.1L V6. At high speeds the Check Engine light will often come on. Scan reveals EGR misfire - cylinder #2. I replaced the EGR valve (with a used one), cleaned out the carbon build up in the manifold, and replaced the gasket. Light continues to come on with the same code. What should I do next? Someone suggested checking the EGR modulator. Any suggestions?

What's the exact code and definition? If its just a misfire, you may just try a new set of wires and plugs. ACDelco should be your number one choice for plugs however. Wires should be lifetime warrenty, at least from a reputable company. Sometimes misfires, come from only a bad wire.

Ditto, the wires. These engine are also known for clogged fuel injectors. You may try some cleaner. My 3.1 Century gets some STP about once a month, if not cylinder 2 will start to misfire. A little STP and it is good as new. Good Luck.