97 blazer 4.3L 190k miles
engine runs ruff in idle and while driving seems to be miss firing a cylinder. runs quiet no knock or pinging of any sort. should i change plugs to see if this could be the issue? they were done about 30k ago. injecters were cleaned about 70k ago. the truck starts poorly in the rain until the engine is warmed up then its fine. any help will be greatly appreciated thanx.

 

When was the last time a full tune up was done. Sounds like the wires, cap, & rotor need to be changed.