i have a 97 ford expedition with a 5.4 liter with 108k miles. my check engine light has been coming on every once in a while and when i check it with my obd 2 it reads either insufficient or excessive egr valve flow. do i need to replace it or can i take it out and clean it to reuse. could the problemm be with any thing else. when the light comes on my engine seems to be very lightly chugging when cruising at a moderate speed. thanks for any help anyone has.