Welcome back, Rweber130.
Igniting 20-year-old black powder motors generally isn't a problem. Make sure the igniters (name from then, starters now) are in good condition and properly installed.
The performance of the motors will have been most greatly impacted by the storage conditions over the years. The best is a moderate humidity and temperature variations.
If these were stored in an attic, they may have seen sever temperature swings that could have cracked the BP grain or separated it from the inner wall of the wound paper tube; either of these could result in too rapid a burn and over-pressurizing the casing. It may do some damage to the rocket its in.
If they were stored in the basement, the humidity could have swelled the casing making it difficult to install in the motor mount tube and possibly weakening the clay parts resulting the same over-pressurizing failure.
If even a new BP motor is mishandled (dropped on hard surface, etc.) it can fail at use. You know best how these have lived. If you have any doubts about the motors but want to use them anyway, find a rocket you don't care about too much preferably with a cardboard or paper body tube and balsa fins, install the motor and announce a "Heads Up" flight. If it blows, you don't want a lot of plastic around it.
Let us know what happens and, remember, we love pictures around here.