I have a 1988 Bonneville SE with the 3800 V6 engine code C almost 185,000 miles. The battery drains far enough down after 2 days of sitting idle so that it won't turn over and start. If I charge it overnight(like I'm doing this week), it starts fine but it dies if I don't keep my foot on the accelerator a little at stoplights. It does seem to idle OK when I first start it up though. Seems to die after it gets warmed up. Idle air control sensor? Throttle position sensor? I took a reading across the battery with my multimeter and I get a little over 14 volts DC but when I checked for AC Voltage it read 30.9 volts AC. Could a couple of the diodes in the alternator be bad? I had the battery(only a few months old) and the alternator checked and they said they were fine. But, they only check to see if the alternator was charging, thats it. Any suggestions would be greatly appreciated.