Possible Alternator Issues, Low Voltage Readings Options

[mzapisek]

Installed the new LED lights on the car over the w/end. Noticed some flickering which led me to start checking voltage readings. I have 3.0 GT clone that I have been sorting through the past couple of years. Car came equipped with the Valeo A14N11 alternator. Currently battery is showing 12.5V at the posts when car is at rest. While running the battery shows 12.3V at the posts. I'm only getting just over 10V at the headlight plug. Obviously this drop in voltage is causing the LED's to flicker.

Bigger question is why I'm not seeing 13.5V when car is running. I've been running the car for the past few months a couple days a week and have had no starting problems so the battery must be getting some charge from the alternator. Is there anything else that might cause the lower voltage readings at the battery while running as well as the voltage drop at the headlights? Really don't feel like dropping the engine to swap an alternator if its not necessary.

Additionally I have been trying to solve a stumble in first gear. The car has weber 40IDA3C's. Could the lower voltage condition also be causing a problem with spark at lower RPM's? The car runs strong above 2500rpm but stumbles coming off idle.

Sorry for rambling. Having fun working on the car but could use some advice.

Thanks.