Misfire at light throttle under 2k

[Stevo-trendy]

Defiantly a air leak had it on my merc when i first bought it & had ran a few tanks of veg through it , turned out to be a perished O ring that the veg had destroyed & generally old age so it was drawing more air in at idle & whilst under braking , you want to replace them with Viton O rings seem to be pretty veg proof , ive just ordered a set so got to replace all 12 on the merc