The level at idle won't come down below 9%,had m8 check it last week and would'nt go below 10% so fitted a new coolant temp sensor as the screw on ECU did'nt make any difference to levels

Have been told you can reset the mixture screw pot by turning screw 4 turns in then 4 turns out then 2 turns back,supposedly this resets it???

Could this be a chip problem,or is there anything else I can check/replace that would affect fueling?

Any help appreciated