When my voltage regulator was failing, it caused all kinds of weird electrical problems. I would check it. It takes 30 seconds to remove it (2 screws on back of alternator; disconnect neg. battery cable first) and eyeball the brushes to see how worn they are. It only cost $15 or so to replace. I have also read many times that on older cars you should just replace all the fuses with new ones because slight corrosionyou can barely see can cause weird problems.

__________________
2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car