slant six ignition issues..shuts off wont crank

changed the ballast resistor and it still stalled.

let me explain it a little better. the car starts and runs just fine. it can be driven down the road just fine. as soon as i stop [like at a stop sign] the car stalls. there is still power because the lights and radio are still on but i turn the key and the car does not turn over at all. sit there for maybe 30 seconds and the car will turn over and start right up.