idle ocassionally drops when clutching in

i have a 1995 del sol vtec (b16a3)

i just replaced my spark plugs with oem platinum from the stealership.
i did not gap them. car definately runs stronger but problem is still
there. i did my research on this idle issue, however there are so many
variables i was hoping that someone more knowledgable would be able to
steer me the right way. could be ignition timing, vavle clearance,
vacuum leak, cap, rotor, O2 sensor, fuel injectors, spark wires etc!!

about 60% of the time when approaching a red light and clutching in,
the rpm drops below the normal idle, only to surge up. i'd say it drops
to 200-300, and then climbs back up to the normal 600. the steering
wheel obviously gives me the shakes since the idle is so low. very
surprisingly it has never stalled out, even though it feels like it
will every time. car never used to this. interestingly, if i blip the
throttle, the idle 'adjusts' itself and i suppose the computer realizes
it was running too low.

the only work i've done on my car recently was bleeding my brakes,
which still feels a little spongy. and any ideas to steer me in the
right direction?

thanks guys