Yep, I have some suggestions as I've suffered from this very thing.
1) Cheapest - Check the vacuum line to the manifold and EGR. They should be encased in a loom up to the point where they seperate to attach to the vacuum points on the EGR valve and the intake. The line on the Intake came off on me the other day and the truck drove me around but acted quite sick. Put the line back on and all was good in the world again. Also consider that it could be the Vacuum chamber at the other end of this same line, so trace your hoses back to that and make sure the connections are tight.
2) $8 + $5 =$13 - Fuel Filter and SeaFoam - replace these may get you back to rights.
3) $200 to $300 - Fuel Injectors - if your truck has hit 100,000 miles then you may want to look into replacing these. Before they (or one) goes out you can experience what you are experiencing. I only say that from my own experience. The injectors are actually pretty darn easy to replace so don't worry about that. I could whip you up some instructions pretty quick. Get the parts from a local auto store or RockAuto.com. Much cheaper than the dealer. After I replaced mine (one had completely gone out as was verified by the dealers diagnostics) my truck runs better than it ever has since I bought it from my Dad.
4) $200 - Plugs, Wires, Coils - easy to replace and did help my truck to be much smoother but I don't think it would cause what your experiencing. Just so you know what kind of bill you'd be looking at for this maint. item
So...that is my two cents. Vacuum leak, fuel filter and injector cleaner, replace injectors. I would start in that order.
1997 Ranger XLT Stepside - 2000 2.5L Engine - Cayman Green - Actually it's running pretty good after new plugs, coils, plug wires, pvc valve and Injectors!!! Runs like a champ!
So, I'll open a homebrew play some Fantasy Football