It could be a number of things. Have you pulled your plugs and inspected them? If possible, label each plug and take picture and post here. The plugs should all look the same, just like this.
If they all look good then it could be a lean condition. Has the filter ever been changed? Might be a good idea to change that. Can you test your fuel pressure?
Also, welcome to the club. If you post where your located there may be a member near by that can help out.