Great that you are trying some work yourself but.

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It may just be the leads but it is more likely to be a cracked coil pack or the earth for the coil pack wait earth's through the mounting bracket to the body.

As for the leads you may need to twist back and forth a little as the boot part that sits over the ceramic of the plug will be stuck if not been off for time.

Edit
I should add that if you pull off the coil pack to inspect and find it is cracked you can dry it out with a hair dryer then fill the cracks with rtv silicone as a short term fix whilst you order a new one.

When replacing be prepared for the screws that hold the coil to the bracket to be rusted solid and need drilling off.

Can't remember the size but if you do a search with my username and coil pack you might find a little write up I did.
