Q: Constant KA issues....

Hi, I have a streetka 2005, for the last 7-8 weeks I've been having a bit of trouble. The engine management light has been going on and off constantly. I've had two mechanics look at it and it's been a misfire on cylinder 1. I've had the coil pack and leads changed twice and after a week or so the problem reappears. Last week the garage change the fuel injector valve(?) and for a week it drove like a dream. This evening, however, the light came on again and it was accelerating really badly, juddering and not wanting to go, there now seems to be a strange ticking noise from under the bonnet. The light comes on and flashes then goes off again and doesn't feel right. Can anyone shed any light on this problem as I seem to be throwing money at this car on a weekly basis 

My car has 72000 miles.
My car has a manual transmission.