Parasitic battery drain - please help

[binkoba]

I have a random battery drain issue I am trying to fix.

The car can sit, sometimes for days and start right up. Other times I park it and the battery is down to 8 volts in twenty minutes.

Here is what I have checked.
1. It is a new battery, plus I have tried three other batteries
2. Amp meter in circuit sometimes shows .2 amps to almost nothing.
3. With the main lead to the engine bay disconnected the car does not go flat.
4. removed and tested the alternator - It passed. Reinstalled.
5. figured it was the starter, replaced.
6 reassembled car moved car, - battery flat after 30 minutes.

Now with the car parked, key out, doors closed, lights off the car is pulling 3.8 amps.

Grrrrrrrrrrrrrrrr..