I have a Maxima 2000. The problem I was having was the car was running very rough to a point of Stalling. The Frst thing I did was to change the 6 sparks And All New Coils. that costed around $300.00 with Nissan Emp Discont. The P0171 & P0174 didnt Not go Away. I did a lot of research and they were all leading to more work more money.
I found a posting here by Guest:trueaussie (Thanks for yr help) had a Suggestion of changing the Mass Airflow Sensor. and since I changed the MAF I too could not believe the difference and the pick up it now has. the cost was $80.00 10 mins job