battery and powersave topic

Hi, i've read many tutorial and guide for CPU tuning e and battary save but i'm not very statisfated with my result.
When i was on stock rom, with power save enabled and 2G mode, my battery lasted 2 days.
Now i have installed a aosp rom, i've downclocked the cpu to 1ghz but my battary lasts in 1 day and half.

It's possible to set the same settings for custom rom and stock rom?
I think the stock rom work on gpu, display color and definition. It's possible to do it.

Thanks to all