Plug wires can be going bad too.....they can look good, but be drying out and cracking...or they just wear out in time and don't work. This is usually 90% rough idling issue. Check your air cleaner too...they clog up. One more thing.....use some seafoam fuel system cleaner.....I'm thinking your f/I.....so sometimes, mineral deposits build on the injectors and need cleaned...or you get a little water built up in the system and it will refuse to clean out...the flush will take care of this...or use heat....its similar....but cheaper...more for collecting and burning condensation out of the fuel system.