Low power

Hello, My car has low power at times. Engine code stored is PO430.
Has the 2ZZ-GE engine.
The degree of power loss varies. Sometimes it is not drive-able, other times it just feels sluggish.
I tried dropping the exhaust during a heavy loss of power, with no difference made. Idea was to take the catalytic converter out of the equation.
Sometimes when the car is running sluggish, it will accelerate without pressing harder on the gas.
I have heard what sounds like a backfire through the intake. Usually when I press in on the clutch to change gears. But sometimes when I am decelerating as well. This is not a constant problem, but when it starts doing it, it will do it several times during the trip.
Thanks for any help you can give me.
John