@Jgood
#1 lose the crankshaft driven fan/clutch for a 15" electric puller fan.
#2 K&N drop in air filter
#3 all synthetic fluids
#4 taper bored or fully bored throttle body
#5 free flow exhaust, plus ¼" from stock
#6 quality set of headers
#7 reduce the weight of your vehicle
Not one of the listed changes will "add power" but each of the items listed WILL reduce the load felt by your power plant... permitting it to operate at a higher level of efficiency.
A "power adder" is:
• custom reground cam with timing
• blower
• supercharger
• higher compression
• more powerful engine
I believe you may find that driving like a truck verses faster or quicker will help your vehicle to live longer, providing increased enjoyment. If that is not your goal, a 302 or 5.0l will fit in your engine bay with some modest modifications (not necessarily simple but many have done it), which while adding some weight, will provide more power if your intent is a hot rod or an off road brute.
@rusty ol ranger
* is correct, a properly matched set of gears and tire size can provide a mechanical advantage.
@ericbphoto
* is super correct as the biggest unnecessary load on these V6 engines is that crankshaft driven fan/clutch