engine mods:

CAI
ported & polished intake manifold
custom 2.5" mandrel bent exhaust
VAFC (6 in / 6 out, 4 cyl, throttle up and to the right - all the sensors report voltage within spec. fuel maps are currently at 0% all the way across, and VTEC at 5,000 RPM)
B&M fuel pressure regulator (32 PSI at idle)

stock parts I have replaced in order to try and fix problem:
ignition wires
spark plugs
ignition coil
distributor cap
distributor rotor
fuel pump
EGR cleaned, and then blocked off
MAP sensor replaced with another used but low milage one.

SYMTOMS
Car hesitates very badly at partial throttle from 2,000 - 4,000 RPM
on upshifts during normal acceleration, car will not go ANYWHERE for about 1 second when I return to being on the throttle
and, most importantly: ignition timing, when checked at 700 RPM, strays randomly from -3 to +3 from stock

WHAT COULD CAUSE IGNITION TIMING TO WANDER?????

 

throttle body positioning censor might be bad or could be a short somwhere maybe a bad ground? i dunno hope i helped

 

the hesitition has to do with the o2 sensor....

once i bottomed out in my accord and snipped two wires from the o2 sensor and it did that from then on...

that has to be the problem, check the wiring first then replace the sensor

 

the O2 sensor has been replaced as well. the wiring looked fine. my digital volt meter running off the signal wire shows a normal reading.

 

Knock senser?