Car's like having a power switch that sometimes I can feel it being aggressive and have more power but sometimes it just doesn't feel right.

What I have noticed:
Case # 1. If car has been turned on and runs smooth and aggressive, it'll be like that for the rest of the travel.
Case # 2. There are times that if I turn the car on, it feels like it doesn't have that much power that I have to put more gas just to feel its aggressiveness. It's like it's hesitating to give power than it has to be.

I don't know if it's called power loss but I can't describe it any better like there are days that it's so much fun to drive as its going fast but sometimes it's hesitant.

Engine is a d15z6 chrome chipped.

 

do the days that the car feels off tie to temperatures outside?
humidity?

there are many factors that could account for what you describe, majority being the Crome program not quite tuned perfectly.
if you bought the chipped ECU or chip itself on ebay or from someone that didn't tune everything to your car then it's even more likely the issue.

it could also be the distributor, plugs, cap/rotor, plug wires, condition of the fuel pump and/or screen/fuel filter, grounds on the engine, the list goes on and on.

 

Im having the same issue. Have you fixed the problem?