1996 Chevy corsica power problems

I have a 96 Chevy corsica 2.2 v4 and it started out after I did a oil change on it. Where you pour the oil into the vehicle right below it is the o2 sensor. Well when I filled the car back up with oil I got some on it. Didnt think of messing it up well about a week goes by and I start having some performance issues when I start the car sometimes it’s really hard to start and others it starts right up but when you start going and you press on the gas after the car has been off it seems like it starts to give power for a instant then just almost does and you let go of the gas petal it evens back out. When I’m at a light it doesn’t like to idle. When your idleing you can hear the engine sometimes switch from almost high revving to almost wanting to die and you have to give it gas or it will die. Sometimes when your driving it it will be normal then all of a sudden your only firing on 2 cylinders or 3 cylinders then all of a sudden it wont give you any gas at all. I put a reader up too it and its saying “bank 1 too lean ‘ but the thing is it could be very many things. I know a lot about cars but I’m not no professional and I definitely can’t figure out what’s wrong with it. Truthfully I’m extremely broke and I’m trying to get my car fixed because I have family things I need to attend to in another town. I’ve changed the o2 sensor and I was going to change the throttle control and the idle air control but when I got them in mail they were wrong so I haven’t been able to do very much more to fix the problem. I’ve did a noid test on the idle air control and when I start the engine it started flashing both red and green but I dont no what that means. If you could help me that would make me the happiest person alive