First step is to find which wire is the signal output of the o2 sensor. Drive the car around the block for 5 min. Then disconnect the o2 sensor. Take your meter (Digital is very important) and probe all four wire. The output from the o2 sensor should be less that 1 volt,do this last step with the engine runing, don't forget to ground the meter. Now, splice a wire from the o2 sensor output wire and run it inside the car. Reconnect the sensor.
Connect the voltmeter, again don't forget to ground it.
Now you are ready to take a drive and see what kind of Air/Fuel mix you got when you drive. This is helpfull when you play with MAF and/or intake sys.
The reading will go up and down at normal engine operation (close loop). At WOT the ecu should go into "Opend Loop" and the reading should stabilize. Lean mix is low volt, 0.1 V to 0.3 V, Avreage 0.4 V to 0.6 V and rich mix 0.7 to 0.9 V. Normaly at WOT you want to get above 0.75 V. 0.9 would be greath.
You car might be chugging at 2900 RPM because of a lean condition. You could also have a look at the fuel pressure. For this you will need a fuel pressure gauge.

Again I hope this helps.

Ghislain