02 daily 35s11?

not so long ago, the filter light ( yellow) lit up, by the time i'd got round to replacing the filter, it had gone out, but i not get the injector light blinking, but only when i am de-celerating from above 2200 rpm, or am driving at speed and take my foot off the gas and let it idle while driving, if i dip the clutch and let the revs drop to below 2200, it clears and i can drive again.
Any clues ??