1994 Ford Aerostar intermittent starting

Electrical problem
1994 Ford Aerostar Two Wheel Drive

Sometimes when I try to start my van, all of my dash and interior lights fade out along with my alarms and I loose the memory of my aftermarket radio. If I wait a couple of miniutes I hear a relay kick in and all of my lamps come back. Is there a relay that needs replaced or is it part of the starter. Acts like battery dead but hood lamp is on when this occures.