Car engine shuts off during drive occasionally

my 1995 Pontiac Bonneville shuts off during drive occasionally.

This happens during a warm or hot weather. The car will simply lose all electrical power, and after it stops by itself, I can restarted immediately.

The car battery gauge behaves erratically almost all the time during warm weather, and comes close to zero very often. Pressing the gas pedal will make the battery gauge go up somewhat.

I do have checked the battery (have a brand new one), starter (new one), and alternator and recieved green in three different shops where they used equipment to hook it up onto the car.

Car does have an oil leak problem and oil pressure gauge often goes close to zero, but I am not sure if this is the cause or the consequence of the previous problem.

As far as oil is concerned, I have to replenish a quart every two weeks (approx 250 miles).

What is your opinion why the car stops occasionally.

Thanks

I would start by checking and making sure all ends of all battery cables are clean and properly attached, making good contact. You also could have an internal fault with a cable. Have someone watch the battery gauge while you do a little tugging and twisting of those cables with engine off ignition on.