Here is a list of verbs that start with FLU.
flubbed, fluctuates, fluctuating, flung, fluoresces
fluorinated, flurried, flurry, flush, flushed
flushing, flustered, fluted, fluttered, fluttering
Hope you enjoy this page of verbs that start with flu and the rest of this verb list site as well.
Did I miss any verbs? Visitors can make this a more useful online resource by listing more verbs in the comments.