[200q20v] Stumbling Problem-Code 2341

[Jeff.Bernstein at pneumaticscale.com]

I have been having a stumbling problem when I accelerate the last few days
and have not been able to determine why.  Every time it does this stumbling
I pull the code and it is always the same--2341 that is listed below.  The
car has run fine for the last 170,000 miles until the other day on my way to
work when the stumbling started.  It doesn't always do it though and it
seems to come and go.  I have replaced the oxygen sensor, cap and rotor and
the ignition coil.  I have also replaced the upper and lower inter-cooler
hoses just as preventive maintenance.  

Does anyone have any ideas on what to do next or has anyone had a similar
experience? 

2341 
Oxygen Sensor Control Limit exceeded, 
fuel pressure too low or too high, intake or exhaust leak, defective
ignition system component, 
intake air leak after air mass sensor, O2 sensor is faulty 
Symptom: CO before catalyst is below 0.3% or greater than 1.0%,
Extremely lean or overly rich exhaust, Spark Plug fouling,

Thanks,
Jeff Bernstein