We have an M3 Evo in with hideous fuel consumption (~8mpg)and a surge/misfire on idle and light load (full load is fine).

We have made numerous checks on ignition/spark plugs/coils/sensors etc and all appears normal. Our diagnostics (BMW GT1) showed a faulty throttle position sensor which we have on order and will be changing in the next day or so.

My questions for the collective wisdom are,

(1) would a faulty TPS cause this much of a poor running condition (especially as the engine can run without it connected...)and, (
2) would this be able to cause the very poor fuel consumption?

Thanks
Sean