How's the fuel tank level? This seems like a recurring fault, so that's probably not the problem, but a low fuel level can cause a lean fault.
The first thing I'd check is the rubber boot which attaches to the throttle body. It tends to crack on the small portion that attaches to the idle control valve.
Do you have or can you get a fuel pressure gauge? I'd want to look at that next, but changing the fuel filter might be a good next step.