I took mine to a mechanic after seeing the mess I had to go through to get the plugs out. He said the front ones weren't too bad but the rear ones were a nightmare, I guess he had to remove the plenum and move some other stuff out of the way to get them all out. If you have alot of patience I would say give it a try and save yourself some money.
Hi SJ and welcome to FTE
At the top of the forum is a thread on replacing your plugs. There are instructions and lots of tips from the other guys on here that have done the job.
Be prepared to have a few hours to do it the first time you try.
They are a pain but not as bad as they look.
Get a quote on the job if you take it to get it done. Last week I got paid 1.1 hours to replace plugs on a truck like yours. Flat rate has come down. It used to be 3 hours I think.
i replaced my wires as i replaced the plugs on my 97 4.6. so i dont know how long it would take to just replace the plugs but plugs arent too difficult except for the #4 (firewall passenger side). The plug wire connector spacers are a pain and take some time. Racerguy did the plugs in an hour, it would probably take me 3 hours but i like to go slow and savor the experience. if not in the tips above, remove the tires and lower the truck near as you can to the ground. this really helps if you an amateur and less than 6 foot.