Questions about a couple of codes

I was getting on the interstate yesterday, i was accelerating hard, and the check engine light comes on. I took it to Checker Auto parts and had them run the scan on it and this is what I got:

P01171-lean during acceleration
P0137- 02 circuit low voltage bank 1 sensor 2

I'm guessing that the P01171 is because of a fuel filter getting clogged. I'm not sure what the other one is caused by. The P0137 was a pending code.

I just changed the intake manifold gaskets, and cleaned out EGR valve, and I also cleaned out the EGR tube in the manifold. The vehicle has been starting hard since I got it, IE it cranks for like 5 seconds when cold before sputtering to life. Starts fine after it is warm. Also had Checker test the voltage output, it was 14.07 under load.

I did a search on here for the P0137, and did not come up with anything. I also looked through the FAQ, but didn't see anything for that code in there either. If you have any suggestions I would appreciate the advice, thanks in advance.