1990 porsche 944 cabriolet.

Hi again.  Still dealing with the fallout from my new engine (grumble).

So for the past week, I have been trying to track down what was
draining my battery.  The previous owner took out the clock, and put in
some kind of green bar that moves around (looks kinda like the
front-end of kit from Knight Rider).  I was told that it had to do with
displaying oxygen levels in the engine or something. Anyway, even when
the car is off all 10 led of this thing are lit up.  So I wondered if
it was what was draining the battery.

I followed the directions for taking out the clock.  The gauge has
three wires going into it: Red, black, and a green wire that appears to
run through the firewall, and possibly to the battery.  It sparked, so
it looks like it carries power.  I disconnected the red and black
wires, but left the green connected.

Later on, while I was driving, the car began to sputter.  Finally I
lost power altogether.  At a gas station, I looked around and noticed
that the fuse for the cigarette ligher / interior dome light / clock
was blown.  I reconnected the "oxygen sensor led", replaced the fuse,
and attempted to drive home.  It sputtered and died again.  The gauges
started going crazy (temp gauge was all over the place, as was the oil
pressure gauge) and the console lit up like a christmas tree, although
the headlights and interior dome light stayed on.

That's where I am right now.

Questions:

1. What would cause fuses to blow like that?

2. What the f**k would cause my gauges to go nuts like that and cause
me to lose power?

3. Tell me, PLEASE TELL ME, that this indeed an electrical problem and
not an engine problem.  Please?

4. Would disconnecting the "oxygen sensor" cause something like this?
Was it happy coincendence?

I have seen this in other cars before when the alternator went out, but
I tested it last week with a voltimeter to the battery.  The output at
that time was 13.7, but the battery just kept draining lower and lower.

Help!