sputtering at idle and low rpm stalls in reverseso

[MYFREE95,240SX]

O.K. so this is my mystery, its an auto 95 240sx with a ka24de. it has been roughly idling for months (6) every once and a while it will stall in reverse. has been getting bad lately to the point that i am scared to back up. when idling it will sputter every so often but will just miss and always recovers. after coming to a stop and accelerating it will skip till i hit about 3 grand then be fine. it starts about 5 min after i start the car never right away. So now a little about my nightmare of repairs i have done recently. 2 new alternators and battery. (charging system issue) plugs are only a couple months old, Bosch double platinum, wires are newer i want to say 1.5 years ago but are all good ones. Just installed new fuel injectors 3 days ago, ummm... exhaust is done from block back. speaking of which my o2 on my cat might be messed up if that would cause this let me know. I'm also confident that it's not anything to do with the install of the new injectors. Thats about it right now. any help will be appreciated its my daily driver and this is beginning to bother me. Also my check engine light just came on today which is why I'm here. kinda think thats cuz of my o2 as i just recently worked on the exhaust and noticed my stock o2 was looking to be replaced. I plan to check my codes but in the meantime i figured i would ask the guru's here in nico. thanks people.

[MYFREE95,240SX]

forgot also the distributer and fuel filter are both new