1999 Dodge Ram rough idle

Hello. I have a 99 dodge ram 1500 sport 5.9 liter and it has a rough idle to it. It starts normal cold or hot and seems to have all its power and drives fine and doesn't die or stall but you can see the rpm jump up and down a notch and feel it in the truck at idle. The check engine light came on so I knew now was the time to have the codes looked at and it said that code po305. I think that's the number 5 piston? So I changed the spark plugs and wires and I will be doing the cap and rotor soon and if that dont work then the injectors. After that I have no idea what to try next can somone push me in the right direction please. There is no coolant in oil and it doesn't run hot and no smell from exhaust.