97 4.0 tune up

My truck is idling rough and getting bad gas milage. It has 130,00 miles and has the original plug wires. I am replacing those and the plugs. Is there anything else I need to replace in the ignition area? I know on older ones you replaced the cap and rotor.

first and foremost, before any plugs are replaced, check out the link i provided for seafoaming a engine to remove carbon build up. http://www.rangerpowersports.com/forum/showthread.php?t=202473 you waqnt to seafoam befor you change the plugs because when you seafoam it breaks up the carbon build up in your engine and burns it off. but it tends to foul plugs, so most people just seafoam before a plug change.[
the equivalent to a cap and rotor on your truck, is the ignition coil. they can go bad. but is unlikely to. though you can get a more powerful one so you can open up the spark plug gap and get a more efficient burn.

Sounds like the old "pour down the throat carbon cleaner" used on carburated engines. One thing about this process is that if the carbon buildup in the chambers is already hard (as in high mileage vehicles) the cleaning compound may not be too effective. But its worth a try.

well with that high of mileage it isnt uncommen for coil packs to ware out and produce less spark..but that usally wont effect it until its cold. it sounds more like a lean misfire which is cause of lack of fuel in the burn... replace ur fuel filter and get a fuel injection cleaning. or dump a bottle or 2 of tecron or motovac in ur fuel tank.. other than that a fuel injection cleaning is the only way to really clean the injecters....DEFENETLY CHANGE UR SPARK PLUGS.. if those are origianal wires and plugs they would be my first consern. if you have done all this and it still have issuse i suggest you test the coils and if they are fine then run a flow bench(it test each injector for flow and resistance.) also make sure you have decent fuel pressure i think 4.0 ranger is around 32-36lbs fuel pressure.