Got my 'stang back today, Ford ended up replacing just the battery, said the alternator was fine. No more flickering while motor is running so I guess it was just a bad battery.
Originally Posted by MarkyMark
The first thing I would do is clean your battery and see if that helps. Power can be lost when you have corrosion or dirty terminals.
Cleaned in back in September, it came back.
Originally Posted by primer2tone
You could check the fluid level inside the battery. If you pop off the caps and you can see the plates, you'll need to add distilled water to it.
Here's an example of a battery low on water. The cell on the left is full, the two on the right are exposing the plates. It could cause low voltage problems.
Did not know that - Thanks for the info. I'll keep it in mind for the future (unfortunately I read this post too late).