I don't have any specific advice, because I think your problem is that you are lacking an overall approach that you can be consistent with.
I would suggest you read the sticky thread here that lists book recommendations for Gentle Discipline. I think two really good ones to start with are "Kids are Worth It", and "Kids, Parents, and Power Struggles". Actually the latter might be a good start, since it seems you and your older son are battling the wills right now, and he's trying to find his "power" at your expense.
I would suggest you read the sticky thread here that lists book recommendations for Gentle Discipline. I think two really good ones to start with are "Kids are Worth It", and "Kids, Parents, and Power Struggles". Actually the latter might be a good start, since it seems you and your older son are battling the wills right now, and he's trying to find his "power" at your expense.