I drive an 2001 jetta tdi and once the winter started i've been having trouble starting ( taking 15 mins of cycling the key warming up the glow plugs before it would start ) and last week the engine sounded like it was "missing" between 1100-1900 rpm then the CEL went on. I checked the code and it was a p0101 and p0402. I looked them up and went ahead and tried unplugging the MAF and the car ran fine so i figured it was the MAF and changed it today. Now with the new MAF it runs fine but i have codes p0401 (insufficient EGR flow) p0402 (excessive EGR flow) p0102 (MAF circuit low input) :S cant erase these codes either. Any ideas? thanks in advance