Nissan Repair: 95 Pathfinder hesitation, obd1 codes, oxygen sensor

Question
My Pathfinder has about 160k and started hesitating last week out of the blue. I suspected a bad tank of gas. I added dry gas, injector cleaner and premium gas. Nothing! I then cleaned the air intake of the throttle body with one of the typical sprays (which revealed a lot of carbon build up) and replaced the cap and rotor. The car began to act better but only intermittently. I noticed that the only way to drive it was to accelerate very hard (about 3k rpm) and after 10 minutes of racing around the problem clears up. Unfortunately it rears its ugly head again after its parked even for a short time. I started reading this list and have since replaced the fuel filter and had a code check from a local station which indicated OBD1 codes 33 and 55. They mentioned the O2 sensor as a possible culprit. Thanks  

Answer
Brian,

I would change the oxygen sensor and the fuel filter.  If your air filter is not clean change it too.  The oxygen sensor is probably the  last thing in the chain and it is probably original.  They get coated and read slow and the computer reacts to the slow reading until it cannot stay in range.  Also, if there is a plugged up fuel filter the pressure will be up and that will cause over richness the sensor detects as will a dirty air filter.