hello, my step-son's 2000 nissan sentra w/1.8 engine idles a little rough at
750rpm then real rough at 1000-1500rpm and then it smooths right out. he said auto zone got 2 codes with the code reader 303 and 1493. does anyone know what these could be and does anyone have a repair manual for this car,or know where he can get one, it seems for some reason a hard one to find? thanks alot Randy