I think you may have just solved my problem mate. the gap it 1.5 mm by the way.
i've had the savage since novemeber. The guy at the shop said it came to him in september (with a a full 1gal of fuel). i havnt changed the fuel since i got it which means the fuel is about 8 months old [X(][X(][X(] .

im guessin thats not good!!! could old fuel really be the cause of these probs (especialy seein as the fuel is that old)..

and yes the engine isn't new.