Land Rover Repair: 1995 disco, air control valve, battery drain

Question
I just bought a 1995 disco with a few probs. I got it running,had alt. rebuilt and installed exhaust manifolds and gaskets,and new battery.Ihave tested batt and alt. with my midtronics analyzer and all is good.I have a battery drain that I am trying to figure out. Also i have a very poor idle.It idles fine then I hear a faint squealing(like a bad bearing) and it starts dying? It is reading a code 45. I checked vaccum lines and unplugged idle air control valve with no change.It does idle better when I disconnect neg. battery cable while running?Thanks!

Answer
You have to pull fuses one by one till you find the circuit that's draining the battery.  Then you have to get the wiring diagram, see what that fuse powers, and see which device is responsible for the drain. There is no automated way to solve that problem in a Discovery