Hi,
The problem surely is not the mAh but more likely the voltage. Maybe the voltage drops and also maybe caused by pulsed current.
For us it is not possible to find the error source, because your description gives only a few (unrelated) data.
It sounds like "i have a car type XY, it works good when i drive to city1, but it has an error when i want to drive to city2"
What we need is a detailed view on your circuit: schematic, voltages, currents, timing. Other related informations like code, pcb layout, pictures, scope screenshot....and very important: a detailed error description. "...is not what i wanted..." is no information for us, because we don't know what you want, and what is not like you expected...
Please try to give more information, so we can better assist you.
Klaus