My 99 Century dash lights are going off for about 5 or 10 seconds and then coming back on. It's happened 4 times in both city and freeway driving, and after I checked the battery cable, which was tight. The engine keeps running normally when it happens.

Anybody know what the problem may be??

Welcome to AF!!

Check for a bad ground wire or ground point. This may be difficult to find but I suspect that may be your problem given the fact that they all go out and come on at the same time. A repair or shop manual will help you find the ground location. Also corrosion may be the issue so check the main ground as well as the other small grounds in the car.

Good Luck!