o2 check engine light with sporatic idle and studdering

[bernzpeed]

fuel injector cleaner?
clean intake?

[Dodobrown]

Recently my car thew a check engine light for a o2 sensor with out any further diagnostic i replaced the sensor with a brand new one. Unfortunately this did not fix my cel and ive been killing my self ever since trying to isolate my problem.

For the past few days ive been scowering the interwebs trying to find any information on reasons for this code (1221) but nothing seems to help.

i have a 1989 325ix with:
new plugs, wires, cap, rotor
long tube headers back (no cat)
new coolant temp sensor
new thermo stat
new fuel filter

the car will drive fine some days with no signs of a problem aside from the cel other days the car will buck and sputter like i have a misfire only under acceleration then eventually run smooth at consistent throttle position. recently now that the weather has been getting warmer the car seems to be over heating (not into the red but 3/4 of the way up).

ive checked the coolant system for leaks replaced the coolant temp sensor and checked the fuel pressure regulator all seem to be fine. Checked for vacuum leaks with about a full bottle of carb cleaner and all seems ok.

any idea where i should look next. im becoming very tempeted to bring the car to some one to have it fixed but i would really like the satisfaction of fixing the car my self.