The main reason that Jon's suggestion of not jumping the gun and replacing all of the ignition parts is a good idea, is that some new ignition parts have a history of being bad. You risk introducing a new problem into the mix if you don't do the other tests first.
It may sound a bit on the nitpicking side, but tracking down two separate problems simultaneously will cause one to pull ones hair out, and all I have left is ear hair.
Don't be surprised if you discover that you already have two separate problems going on already. You definitely don't want 3 at the same time.
Carl