question about my 89 accord

I just recently got an 89 accord sei for a daily driver, and all was well for a bit. I love having a 5spd to drive around again finally, and even for an 89, this car drives like new. Ok heres my problem. When my engine comes up to temperature, i start to get occasionally bogging of the motor at idle, plus the phantom slight revving of the motor, and under heavy acceleration or immediately after a downshift, the motor feels like it misfires. I was under the impression that it could be one of the o2 sensors, since the car only acts funny after it comes up to temp, but when I checked the diag. codes on the ECM tonight, I got code 6, which according to the chilton's manual I got along with the car, means coolant temp, so I'm entirely baffled now. A little help anyone?

Oh, before I forget, this board rocks.