when you replaced the voltage regulator, were the brushes very unevenly worn down, or ok looking?
yes, first off get yourself a digital meter. There are some basic tools you just cannot do without as an alfa owner!
then follow rogerspeed's advise and remove both battery posts and clean, especially
the ground cable screwed to the trunk floor.
Next I would clean the connections on the main electrical junction with the thick red wires going to it, under the hood on the left inner fender: undo clean replace. The green wire is the alt. wire, the big reds are starter wires.
with your newly aquired digital multimeter (
test the battery voltage (your dash guage is not accurate enough for this): put the voltmeter set to 20V range on the battery....a good healthy battery should be 12.6V
now start the engine, get someone to hold the revs at say about 1200 and again test the volts across the battery.....if all is good with alt charging, you should get about 13.8 - 14.4 volt.
with throttle: press the gas pedal to the floor, now check the throttle control flap under the hood....can you still move it some with your fingers?
PS you will get a lot more views over in the spider section if you move this there...