Nissan Repair: exessive fuel, fuel pressure regulator, mass airflow sensor

Question
I have a 95 nissan pickup 4x4 with the 6 cyl 3.0l engine, it it running really rich and i cant figure out why, ive tested the mass airflow sensor and replaced the o2 sensor and nothing has fixed it yet i do know that the injectors are staying on for a couple ms longer than they should be, i need help!!

Answer
Tim,

I would check the fuel pressure to see if the fuel pressure regulator is blown and is in need of replacement.  If the pressure is fine and the regulator is working.  I would also check for leaky injectors.  If they are leaking the fuel pressure will drop off fast when the key is turned off.  If the injector pulse width is loo long then the distributor needs to be replaced.