Girlfriend has a 2001 Legacy GT, ran great for the last 2 years, more or less. Car sputters and stalls when cold out, after startup. Threw two codes, P0139 and P1507. First thought it was the MAF, but this engine has a MAP sensor, as far as I know. She says her mechanic went through it not too long ago, and they replaced the gas cap, lol. I don't want to replace the downstream O2 sensor, as I don't think that's the cause, but correct me if I'm wrong. Car has 183,000 miles on it, we're in upstate NY right now. Thanks in advance for your advice, never worked on Subarus before.
