Well, my friend who actually has a 98 also had this problem. Of course she has money and took it to the dealer. She said they replaced the spark plugs, maybe wires too, she doesn't remember and has lost the receipt so I can't figure out what they did. Yeah, I heard this is a fairly common problem too, but no one seems to have a solution yet except for the dealer.
Yeah, my air filter is about several months old, new Bosch +4 plugs (it actually seems to run better on these than the old iridium plugs - better low end power but I think weaker on the freeway, maybe it's a hot plug). The only thing I haven't changed is the battery - but there's no problems cranking at all and the car does start, just doesn't stay alive. Maybe it's a sensor or something.