89 4cyl. S-10 sometimes wont start/bouncy idle?

its not my truck its my girlfriends dad who owns it....its been a great running truck all of its life from what im told. well he started having problems a little while back and now it wont start from time to time, and when it does run it has a bouncy/rough idle. i suspect something with the ignition,or a cold idle valve(if the truck has one). he's not a dummy when it comes to vehicles so i would imagine he has checked the basics. does anyone know or have had a problem like this? he says the truck has a 2.5 liter and i know its got one injector in the throttle body..that should tell ya the engine.

When no start check for lose of fuel pressure or lose of spark.
Got and stored codes?