My 1997 Mustang Cobra has 78k miles. When tested, the alternator put out 130amps, the cars voltage was between 13.75 - 14.40, idle at 800. The battery isn't the best, was killed a couple times from sitting but passed a test.
After driving a few minutes I am getting a dip in the voltage gauge (The more accessories I turn on, the lower it goes), and when the car is at idle it becomes a little rough(bouncing between 775 - 815).
Car has a new IAC, no codes, no vac leaks(smoke tested), and no performance issues when driving. Can the battery be causing this?