Ho so i buyed audi 2012 year , has 97,000miles done . when drive longer time on road it goes limp mode . The problem comes faster if i push harder on revs . It starts all good for fist 20 min but after that when drive a car you can start hearing small pump near engine keeps working louder and louder and harder than you know that limp.mode gonna come . You have to stop car and turn off engine wait for 2or 3 min and its ok again for short time . I changed all 3 pumps in car all 4 injectors ,Regulator ,but it didnt fix problem fault code is p008700 fuel rail/ system too low .permanent. filters all changed pls help because i spend a lot money .