1996 Mitsubishi Eclipse jerking

Engine Performance problem
1996 Mitsubishi Eclipse 4 cyl Front Wheel Drive Manual 127k miles

when I start the car the rpms bounce up and down violently and the check engine light flashes every time they bounce.(Check engine light on because I got new headers and o2 sensor messes up) after it is start it like bogs out and dies after a couple minutes. Ive had this problem before and it went away since then ive gotten new alternator, battery, and its had the head gasket changed out. For the first 2 weeks I got it back it was running fine until a couple days ago. When the problem first began I changed the spark plugs, plug wires, coil pack, fuel filter and it had no affect. All parts have less then 600 miles on them. When I am driving and release the throttle it starts to jerk more violently then usual so I have to step on clutch. Anybody any ideas I need help!