Weird electrical gremlins

[James]

OK, the latest in my C900's eccentricities.  Possibly related to the stalling problem?

The short version is that it dies when there's too much electrical load.  A few examples:

- Driving along at constant speed, esp at low revs, if I put two of the windows down / up the radio dies and the car stumbles / stutters
- Rolling slowly into my garage, I hit the brakes and the car often dies
- Without much electrical load it idles reasonably smoothly (for a 900).  Turn the lights, fog lights, HRW on or put the roof up / down and it nearly dies.  In fact often it does die when you operate the roof.

So far we've replaced most of the vac lines, cleaned the throttle body and replaced the idle control valve. 

Ideas?

[Max Headroom]

Is the alternator doing it's job? May be worth looking at how that is performing when a demand is placed on it. Check simple stuff like battery earth and that the bonding/earth-strap twix engine block and chassis is in good condition

[phoenix]

Time to start checking the earth leads- particularly the one on the front chassis member behind the radiator. They get corroded and consequently resitance rises which can lead to the problems you describe.

Also check the voltage drop between the +ve battery terminal and the distribution block on the right hand wing.