ErrantVenture11

I recently had the local Valvoline place hook my 2000 4cyl. Protege to a OBDII to find out what my check engine light is for, and they said the code was for a lean condition. You can't really tell while driving, though to me it seems to be a bit more lethargic at the low end then I am used to. And every once in a blue moon it will shudder for an instant at a stop, like it wants to shut off.

Are there any known issues I can check myself to see if they are the problem, or should I just take it to a dealer? I already ran through some fuel system cleaner just to be sure it wasn't simple blockage in the lines.

I mistakenly posted this in 3rd gen. engine/drivetrain modification forum, so if it looks familiar, sorry.