2009 dodge journey SXT, v6, about 117,000 miles. Got MIL on about three years ago. Check OBD code, It was p0406. cleared the code. Within 3 years, MIL on about 4 times. Meanwhile, gas mileage was down about 10%. Last week, I replaced the EGR valve. Felt a little rough on idle. Gas mileage improved 5% better. Then p0441 was on (no P0406 yet). Besides replaced EGR valve, I did clean the throttle and disconnected a vacuum line . What causes P0441? any advice is welcome.