A brief comment on the Romer´s Narrative Approach
As Sumner pointed out M2 increased c. 6% during Greenspan's tenure. But the demand for money increased, i.e., the proportion of M1 to M2. It hit an all-time high in April 2008. Banks don't lend deposits. An increase in gated deposits shrinks gDp, shrinks velocity.
Inflation was a concern because the U.S. $ was dropping due to the large trade deficits (primarily the cost of oil).
And regressions don't work because the FED always covered its "Elephant Tracks".