Flashing Ebrake AND Battery Light

I just recently had a 110 amp alternator put in my car along with an optima battery. this was supposed to take care of some electrical issues in my car (amps, subs, dimmed headlights, etc.) well now my battery and brake light are flashing at the same time when i drive the car. sometimes the lights will stay on continuously and other times they will stay off. when the car is idling the lights stay on, but are very dim. when i give the car gas and the rpms go higher, the lights start to get brighter and flicker at a faster rate. i also have el glow gauges for the dashlights and for my thermostat lights. the dashlights sometimes flicker when i first start the car, but after i give the car some gas they are normal. However, the thermostat lights constantly flicker, not sure if this is related to brake and battery light (they flicker when those lights are on). Also, headlights get brighter and flash at the same time as the brake and battery light. i just replaced the ecu w/ another stock ecu from a junkyard and this doesn't seem to have fixed the problem. could the problem be with the high output alternator and im getting a surge of power from it or do i have some major electrical problems? should i go back to a stock alternator?

sounds like a bad alternator, how are the belts?

one belt sounds like it needs to be tightened, but i think it may be the alternator too. i just had it installed like 3 weeks ago, but it's been doing this almost the whole time i've had it in there. the alternator was custom built so maybe the guy who built it screwed it up. i will double check. one other thing is that i had the mechanics at one shop test the voltage when it was idling and he said that it was charging the battery. would it be possible that it could undercharge the car as i give it gas?