If ALL the lights flicker, it almost has to be one of your battery cables.

Will he lights flicker even if the car is not running? (You can bounce the car up and down.)

I would try to wiggle both ends of each cable with a moderate electrical load such as parking lights. You can try this without running the car. If I got no results, I would try wiggling other parts of the cables.

BE SURE TO TAKE SOME SAFETY PRECAUTIONS SUCH AS;

DO THIS IN A WELL VENTILATED AREA, PREFERABLY OUTDOORS.

I WOULD WEAR SUBSTANTIAL, LONG SLEEVED CLOTHING AND FACE PROTECTION.

IN THE WORST CASE, WORKING ON THE MAIN CONDUCTORS OR BATTERY OF AN AUTO EXPOSES YOU TO THE POSSIBILITY OF ARCING, SPARKS, HOT METAL, HYDROGEN GAS EXPLOSIONS, ETC.

I've had to perform first aid on a victim who had a battery explode in his face, it's no bargain. (Flush eyes with water for 15 minutes.)

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2 8s & 2 7s 600,000 miles total