The first thing to do is consult your owner's manual regarding the service maintenance schedules listed there. The "Severe" service schedule is typical for most drivers in the central valley. What is the mileage on the vehicle?
The 4.7 in the Ram (at least for 2004 model year like I have also) calls for copper spark plugs only, that need to be replaced every 30,000 miles. It's easy and I did it myself in about 90 minutes. I have read mutiple threads that warn NOT to use anything else, as does the owners manual, no platinum, etc. I don't know why, my aunt's 2004 Jeep with the same engine DOES use platinum plugs. All eight copper plugs were $12 at the dealer. I only have 31,000 miles on my 2004 but every time it moves it is hauling something or pulling an enclosed trailer or a landscape trailer for a property company. I just changed both diffs, the transfer case, transmission, and coolant out for the first time, going by age over mileage. I would think these should be done every 40,000-60,000 miles, though the manual says the coolant can go 60 months or 100,000 miles I think. I change oil and filter every 5,000 miles or about once a year, and use Mobil 1 5w30.