Bad starting D15B2

If my CRX has been sitting more than 5 hours, it acts funny. The check engine light will come on, and the idle will be rough. If I let the car idle or drive for about 5 minutes, then turn it off then on, the engine light goes off and every thing is fine. Oh, when I drive with the engine light on, no matter how hard I press the pedal, the RPM's go up, down, up down, like it has dirty injectors. Cant figure it out!

My other CRX that i still have does the same thing. It's a Si (D16A6). I havent been able to figure out what it is but if you figure it out, let me know cuz i need to fix the problem too. I will do the same if i figure it out. Thanks. :)

Do you have enough fuel pressure? When my fuel pump went out, it had problems similar to that. Step on the gas and the engine wouldn't respond. Rpms would jump up and down.