Deya has good advice. Also on your head unit, you can change it so it will show 3second average which will help smooth it out. And part of it is pedal stroke,over time as your pedal stroke gets smoother,so will the numbers.

I got my power tap after being off training for 6 months due to illness,it has taken about 4 months to smooth my numbers out so they stay closed( today I avg 170 watts for 48 miles but while riding it fluctuated but a smooth fluctuation based on wind/paceline vs. A few months ago where different points in pedal stroke created fluctuation) .

Any questions, ask and I'll try to figure out an answer.