I've got a 2004 X3 with a possible electrical issue.

The car will be on, then after about 20 seconds the alternator and battery light will come on, and then there will be no throttle response. The car will still be on, but it won't move. Sometimes it drives fine for the day.

If you let it sit for some time (maybe overnight, it varies) it will turn over and drive fine for a while. It's intermittent but requires hours to drive again.

Here are the things I've checked:
- It does not have bluetooth or navigation.
- All the fuses are fine
- There is no Check Engine Light
- Battery and alternator passed tests at Autozone

The odd thing is there's no Check Engine Lights.

Does anyone have any suggestions? I took it to a mechanic that's worked with my family for years but he can't find anything wrong.

Thanks!
- Jason