SES light issue on recently bought x5

[lucasbm]

I just purchased a 2004 x5 3.0 with 97000 miles. A day after I bought it, I filled it up with Premium fuel and shortly after that the check engine light came on. Checked the fuel cap and the light continued to stay on. I took it back to the used dealership (keep in mind this is a used lot, not a BMW dealership.) and their tech said it had 2 errors that were both saying the engine is running lean. I want to say the codes were P0171 and P0174 but I'm not 100% sure. The engine has never "rode" bad. Anyway, the dealership replaced part of the intake hose and said it was cracked and was sucking in air in the wrong location which was causing the error. Drove the x5 without the light for about a week. This morning I fueled up again and after about 30-40 minutes of driving, the light came back on again. I haven't checked the code yet, but assuming it gives the same code, do you think it is really something with the intake? Is it coincadence that the light came on both times shortly after fueling?

On another note, The red oil light will flicker when I'm coming to a stop. It will only illuminate for a spit second and go off. I plan to change the oil and filter ASAP to see if this helps correct the issue. I've read on other topics that BMWs are really picky on the weight of oil you use.

Any advice will be greatly appreciated and let me know If you need any further information to help with diagnosing the issue. Also, any suggested maintanence I would need to look into doing with the 100,000 mile approaching would be great. This is my first BMW and I'm going though a learning curve with how tempermental these things are to keep running in tip top shape.

Thanks,

Luke