if you have a 2.7 or 3.5 liter motor then yes you do. if you have a 5.7 liter motor then no you don't. it shouldnt be that bad. they usually come off with few problems. it may take you a couple hours to do it tho, but its not hard. just time consuming.
No you do not have to remove intake manifold. There has to be a way to get to those plugs. It may take a special tool that you do not have. The best thing to do is go to the auto parts store and ask them. They are always glad to help.