at haphazard
at intervals
at irregular intervals
at random
brokenly
by catches
by chance
by fits
by jerks
by skips
by snatches
capriciously
carelessly
desultorily
disconnectedly
discontinuously
eccentrically
erratically
flutteringly
haltingly
haphazardly
here and there
hit or miss
in snatches
in spots
inconstantly
indiscriminately
infrequently
intermittently
irregularly
jerkily
lurchingly
nonuniformly
occasionally
off and on
patchily
per saltum
promiscuously
quakingly
quaveringly
quiveringly
randomly
roughly
saltatorily
shakily
shudderingly
skippingly
sloppily
spasmodically
sporadically