[urq] URQ intermittant duty cycle

[DGraber460@aol.com]

My relatively new to me URQ has baffled me when it comes to getting it  
dialed in. I have used every trick that worked on the wrecked car and it  responds 
but will not completely dial in.
Tonight I monitored the O2 sensor and found that when the idle (or  
acceleration) goes weird, the O2 signal goes to zero as well. Cool I thought, so  I 
replaced the O2 sensor and thought I had my smoking gun. No Joy. It still acts  
up, with the duty cycle going to 99 and O2 signal going to steady .003.
When everything is good the O2 reading varies from 0.2 to 0.7 and the freq  
valve buzzes away. When things are bad the FV goes dead quiet.
It is sporadic, and on some instances revving the engine will bring it  back- 
sometimes not.
What could cause this? Is this the dreaded ECU duty cycle signal failure?  If 
so, why would the O2 signal go south? Do I have 2 equally bad O2 sensors?  
Wiggling all the wires has no effect.
TIA 
 
Dennis
Denver