Hey im new the forum. I bought an ef xr6 5 speed last year around august. It ran great up until 3 months ago where at low rpms from 1200-2000 you put your foot 1/4 to half way down and it'll start jerking and coughing and half backfiring but when you put your foot flat it doesnt do this. It has a cam but it had this problem before the cam and its tuned by a j3. I replaced plugs and leads last week. Anyone have an idea of the problem?