Passed my test a few weeks back... Been driving my MK4 fiesta S reg and it had a slight mis-fire underload.. So changed the spark plugs.. and it stopped... but then it returned again after doing a few miles. so i tried to live with it.. but then it started to mis-fire properly.. at all times just running on 3 cylinders.. So i drove halfrauds and got some new leads.. Fitted them and all was fine.. until it started to mis-fire slightly under load.. Car is quite jumpy in the 2000-4000 revs in gears 2-3 mostly.. Tried checking the MAF sensor but it doesnt even have one haha So... Is there anything you recommend i dowhich will fix the problem, Except change the coil pack which im planning on doing once i get paid..?