ok, here is the deal. i have a 94 del sol vtec with a jdm b18cR swap. i'm running hondata and i've been tuned. also running RC 550 cc injectors with the resistors wired inline (peak hold). only thing changed in the motor is toda 12.3:1 CR pistons.
car has a strange stutter problem that only seems to happen once it is warmed up. on its way to warming up, it runs fine. when sitting at a light it will hold idle at ~700 rpm like normal, then do a drop, then pick back up. every few seconds it will do this, seems pretty random. also, sometimes when taking off in 1st, it will stutter, then i have to push in the clutch, give it gas, then it seems ok and i can pull away and drives like normal. everything else runs fine, it is only at these times it does it. however, i think it may be doing it at very partial throttle, say 10% when cruising. i have replaced the cap, rotor, plugs, wires and fuel filter. nothing changed. i did swap the coil and ignitor out of my old b16 into this distributor and the problem seemed to go away, but is back again. i'm afraid it could have just been my imagination that it was fixed? but it did seem better. that was maybe a little over a month ago. when i check the timing on the car, the strobe will not flash during this stutter time, like its an ignition miss. anyone have any ideas? i'm going to borrow a friends distributor this weekend and see if that fixes it, but it seems so random i'm afraid i'll think that fixed the problem when it really comes back.

 

i have replaced the O2 sensor, so far symptoms appear to be gone.