1996 Honda Civic Sensors and Altenator

Hello I have an 96 Civic EX, auto. I have 4 codes, one is p1298, one is my vehicle speed sensor, and the other 2 consists of both my 02 sensors. I also have like a squealing pulsating sound coming from my altenator in which my lights pulsates with the noise. Also I was told my ECM my be bad.

Just tonite my car died on me at idle so I checked the the battery and it was dead so I put it on a charge and rechecked it and it was good so I out it back in the car. I hooked up everything and started it and while using a multimeter I noticed that the battery was draining. I heard no squealing pulsating sound at all so I revved the throttle a litte bit and the squealing came back and the battery began to charge. Eveytime after that I start it and not squealing and pulsating noise and when I step the gas it all comes back and semmigly works with the noise from there on. While running it fluctuates between 13.00 and 13.99. It starts high and then drops.