checked battery changed starter checked starter checked fuses relay clicks sometimes it does not click

I have changed everything that I can think of of this van and the lights are still on

Changed my thermostat and now it won't bleed out all the air. Get heat out of the back of the van but not the front.

Jumping it was unsuccessful.

The signal bulb is not burned out. This happens off and on all the time. Sometimes when the radio/clock light goes out and on other dash board lights go out too.

What seal would have blown out, without blown up the engine. And it still starts.

Remote switch has been checked,ok. The receiver not working on any doors.

Evaporative System and Heated oxygen Sensor. So what can I do about that.

The light is on after the car ran out of fuel. Now the light remains on. I just bought the car to a dealer without warranty. The car has 160,000 miles. Runs nice and is very well maintained. I was reading the user manual but didn't find good help.
Can you give me some advise on this problem. The car has the gas tank and I recheck it, oil ok. Two weeks ago I put gasoline of different class because was the only one available.