Changes in pressure equates to fluctuations in flow. When flow changes, the burner can't react quick enough resulting in water temperature fluctuations and spikes.
Enabling the well setting evens out the burner operation.
It is quite easy to turn on following instructions on that page, changing the C to a S (set)
A NR 180 in Indiana? Hope it's a 1 bath house, 150,000 btu unit for that region is undersized for any more than that.