1996 Nissan Maxima Stalls

Engine Performance problem
1996 Nissan Maxima 6 cyl Front Wheel Drive Automatic

My 96 Maxima has recently started stalling out sometimes at idle, sometimes while driving low speeds, and sometimes at takeoff, the rpms will jump up and down, the gas pedal response is sluggish if any at all, these happen intermittantly. Most times I can turn ign switch off, turn back on and let sit for just a moment and it will start and run fine for a time, then it acts up again, sometime it will be fine till I get where i'm going, and sometimes it just goes dead again immediately. I have replaced the fuel pump and filter, the platinum plugs are maybe two years old, and I just replaced the battery with an 850 CC amp. Thought maybe it was fuel reg, (after changing pump), but I disconnected the vacuum line from the reg, and it ran fine for about 10 min and started stalling and choking again. I dont know what else to do, any suggestions.