subliminalyzok

So I have read most of the threads already relating to this and they all sound close but not really my same problem. I am new to Nissan, but have experience with 80s Hondas. The truck will start fine, warm up without dying, even let me drive for a little bit and idle in neutral at lights, but all the sudden it will start dying in neutral So I have to feather the gas to get it to not die. I drove it today and that's what happened, except it starting running fine again when I got back home and was backing up into the driveway after it died. The emissions system is gone and all the vacuums have been sealed. Any ideas???