I will preface this question noting that my Pathfinder has 252,000 miles on it. Up til last week the only thing I have had to do is replace some ignition coils and plugs. It is my wife's ride. She said it was lacking power. I did notice when she started it, it was dragging. Had the battery checked and it was going bad. So I replaced it. Then it started dying when started after sitting. I drove it and noticed the power problem and dying.
I took it to my auto supply store to have them scan it and they said it coded a variable timing solenoid, right side. So I replaced it. When I started it after replacing it o got 3 lights on my dash, ( brake, AT oil temp, Battery). From what I read that was the alternator. I replace it. That fixed the 3 lights but it is still dying after you start it. It runs fine for about 10 seconds then Dies. I replaced the fuel filter. Still dies. I can keep it from dying if I pump the gas pedal enough. It seems once it warms up it will run but the idle is erratic. And driving it I can feel the lack of power come and go.

First, check the charging system and make sure it is charging between 13.2-15.5 volts. If not, you still have a charging system issue. If that's good, it's possible that you may have to perform and idle air volume relearn. It can be a real pain to do, sometimes, without access to a scan tool and trying to do it via the "manual method." The factory service manual has the procedure and Nico Club's site has downloadable manuals for free. Sometimes the IACV-AAC valve will short out and fry the circuit for it inside the ECM, causing idle and cold stalling issues, but it almost always triggers a P0507 code when it does.

Beings I do not have a scan tool. I will take it to the garage to see what they say. Thanks for your help and I will let you know what I find out.