it looks like an xr3i is that right?

if the revs are high i would suspect an air leak is part of the issue, does it have the start issue all the time?, i.e. hot, warm and cold?

have you had the co checked?

im in minster m8, no expert but ive had a fair few 16i's, 3i's and rst with faults and sorted them all, its a fairly simple setup and on a 3i is normally very reliable