PROBLEM With EGR system & a/f ratio ! ! !

[usaqmuri]

civic 94, d15z1 vx (vei vtec-e)

problem #1
when i disconecting EGR velve sensor & EGR control solenoid valve, check engine does not Light On is it normal?



problem #2
engine work on rich A/C mixture, it can see on spark plugs (i replaced spark plugs many times) now standing ZFR4F-11 (NGK)

problem #3
engine lose power, it feels good when i ride at hi rpm.

problem #4
Fuel consumption 9-10 litres/100 km (23 MPG) in city. hwy (30 mpg)

replaced:
oxygen sensor.
map sensor.
throttle angel sensor.
new changed oil in engine & gear box (+ oil filter)
AIR filter
OIL filter
Fuel filter
Ignition Timing is ok

please tell me all reasons on this problems