What would cause all the lights in my car to flicker?

i have a 2000 plymouth neon and ive noticed when the car is running the headlights, dome light, dash lights all flicker when the car is at idle and gets worse when the car rpms increase. Also i have a problem of when im cruising down the road and shortly after the torque converter locks up and i give it a little more gas the car feels like its jumping around and when i turn on my lights it gets worse and also when im sitting at a stop light the rpms drop below the normal level and the car shakes real bad and gets to the point the its going to stall but then jumps up to normal rpms. can all this be caused by a bad alternator which ive done a complete tune up, oil change, and ran several things of injector cleaner through the car. i really need advice this car is my only form of transportation.