Nissan Repair: sr20 part throttle o2 reading, throttle position sensor, air control valve

Question
I have a sr20det motor in a 240sx . o2 monitoring gauge (LM-1)when idle reads correct,when accelerating reads correct, BUT when cruising at any speed for more than a few seconds the O2 reading goes off the chart and the car feels sluggish and O2 reads severly lean until I press the gas a little.so I have to keep giving it gas back and forth.I thought maybe the TPS was the problem but dont know maybe AIC valve. help me out please.

Answer
Shane,

Sounds like the throttle position sensor to me or the air meter screwing up.  The idle air control valve (motor) is used for idle and transition to and from idle to include compensation for power steering activation at low speeds and increased load like airconditioning and fans kicking on (load on alternator).  So, for my thinking you have something going on with the TPS or your air meter.  Now, I would do a fuel pressure check to see if the pressures are within norm before I plunked any money down for parts.