About 6 months ago I had a O2 sensor problem on a 1991 Accord EX. I replaced the O2 sensor and the problem went away (rough running after about 5 minutes). The diagnostic codes pointed me in the right direction on that episode. Now a few days ago the CEL light started coming on as a flash but not remaining on. Today the old problem returned with a twist. After about 5 minutes the car starts running rough with a loss of power. If I continue at low speed eventually it clears up AND the CEL comes on. As long as I run it with the CEL on everything is fine. If I turn off the ignition the CEL goes off and stays off until the above routine is done again. I've jumped the code connector by the glove component and the manual says that should make the CEL light stay on and give me the code. The CEL light does not stay on even when jumped. Any clues?