homelite vac attack 2 30cc only runs at half speed ?

Possibly - make sure the cut is away or shrouded from the chainsaw metal case - take some similar diameter pipe, cut down the side and tape this round the fault. The problem is most likely to be a dirty air filter - most are washable in water or the "H" carb setting being too fully out, try one turn out once the filter is clean and dry.
If this fails, it may be a blocked main-jet

steve
March 2009