Truck starts fine and idles ok. spits and sputters at 2000 to 2500 rpms and will not rev over 2500 rpms. i've already replaced the MAF sensor.

I had the exact problem with my 1998 Nissan Frontier with the 2.4L engine. Replacing the cap and rotor may illuminate this condition for a short time, but it is only temporary fix. You may notice that this condition usually occurs in the morning or whenever there is high humidity (Did it rain last night?). It may be that the contoured rubber seal that's located at the base of the distributor cap has failed allowing moisture inside the cap. The seal alone is not available through the dealer so you must replace the entire distributor. New distributors are sold on eBay (under $100) and will include a new cap and rotor. It's any easy job to replace the distributor, before removing the original distributor, make sure to mark the location of the rotor in relation to the distributors body and side of the engine and install the new distributor with the rotor pointing in the same direction as the original. You'll need to use a timing light to set the correct timing as listed on the information plate under the hood. My truck ran great after this was done and I no longer experienced the sputtering and misfires that you mention. Hope this helps.

CLOGGED FUEL FILTER OR CLOGGED FUEL INJECTORS.WILL CAUSE SPUTTERING AND MISFIRE.LEAKING EGR VALVE WILL CAUSE ROUGH IDLING SPUTTERING.