Hi Dan, I'm in Howell.
With that many miles and a low budget I'd just focus on general maintainence items. A good induction cleaning, filter changes, and making sure no brakes are dragging would be just as effective as adding on hi-po parts.
I'd do the following and in this order:
Buy two bottles of "cheveron with techron" cleaner. At the next fillup pour them both in and fill with shell 93 "v-power". I've done this many times and it is indeed effective on motors with a lot of build up / miles. And don't go cheap on the pour in cleaner. Use only the "techron" stuff.
Now, get an old tooth brush and a spray can of "throttle body cleaner". Not carb cleaner! It must say *throttle body cleaner*.
Take the TB off and clean it with the spray and tooth brush.
Using only the spray clean your MAF. Be careful with it and only gently spray the sensors wires. GENTLY!!
Dis-connect the neg terminal of the battery. Turn on the headlights and ignition then wait ten minutes. (this clears the KAM) Turn both off and re-connect. The start the truck and let it fully warm up. Then put it through the four idle learning steps. (search here at R-F)
After that tank of fuel is run down replace the fuel filter.
Check for a dragging brakes and tire pressure.
Now IMO your ready for aftermarket mods. IMO the best place to start are spark plugs. Many here at R-F are biased towards the stock motorcraft plugs. They are indeed good plugs, but I'm a big fan of Bosch +2s for stock motors. Some here report bad experiences with them? Here is the very expensive plug I use: MY PLUG WEB PAGE
(denso IT series)
My next suggestion would be a stock or aftermarket coil & plug wires.
Next I'd suggest a tune via a chip or flash devise. (use lasota racing)
Next I'd get some underdrive pullies. (excellent bang for the buck IMO)
Unless your into high rpms an awful lot a aftermarket intake is not a good bang for the buck.
Check out my web page linked below my sig.