Thanks for all the info everyone.
I am going to look into getting ISTA+ (hopefully I have an old laptop that meets the system requirements) as reading up on it convinced me its the way to go. Though it does look like a huge process to install and learn...
In the meantime, I found a useful YouTube video on how to diagnose the ignition system. Didn't know that the engine could compensate for a faulty ignition that much and also that I could unplug coils as the engine is running without screwing it up... Fingers crossed for that one.
As always, thank you all for your responses thus far. If anyone has any more ideas or further opinions, please feel free to post as they will be welcomed. I check the forums pretty regularly. I will update here if I make headway or if anything changes.
Cheers,
mmns