having issues on cross country drive

bear with me as i explain the history...

my wife and i have a 2001 330cic with 84k on it. we are currently stuck in lincoln, nebraska for the weekend about halfway through a cross country trip from nyc to los angeles. about 5 days prior to our trip the 'service engine soon' light came on and the codes were the typical po171 and po174 -- running lean on bank 1 and 2. i made a mistake of initially taking it to a very local service station first (non-bmw). the mechanics pulled the codes, spent 25 minutes looking over the engine while it was idling, and said they think it's safe to drive across the country. by the way, there are no symptoms -- the car is idling fine, no "whoosh" sounds, normal power at all rpms, etc... i didn't trust their diagnosis so i drove it to a bmw indy shop (don't ask me why i didn't do this in the first place). the first service station had cleared the codes so the indy shop mechanic was, according to him, diagnosing it blindly. he ran a high pressure smoke test and ended up telling me that he highly doubts it's the o2 sensors. that the fuel filter and coils are fine. he didn't find any vaccuum leaks. so he replaced the mass air flow sensor. the car ran fine and continues to run fine, but yesterday while in topeka, kansas getting ready to leave in the morning the service engine soon light comes on again. there's one bmw dealer in topeka and no indy shops. we took it to the bmw dealer but he said he could only look at it for 5 minutes -- too busy to service it within the next 48 hours. after a short check he also said it seems fine to drive since it has no symptoms. we drove about an hour but decided that rather than going another 5 hours to denver it would be smarter to take a detour to lincoln, nebraska where there are indy shops. the guy we are dealing with now has been working on german cars for 20 years and is the head mechanic for a few local racing teams. he pulled the same codes (171, 174) and it said bank 5 is running lean and bank 6 is borderline. he spent an hour looking for cracks in hoses, pcv, etc... and ultimately did a "plastic bag test." bottom line, he THINKS it's the valve inside the pcv getting stuck and he has ordered a new pcv and i think 4 corresponding hoses. the parts are coming in monday morning and he said it's a 2.5 hour job to fix it. he didn't reset the service engine soon light so when we left his shop last night and were driving around a little the light remained on. the car continues to have no symptoms. this morning we were driving around and the light went off. we've stopped, started, and driven the car several times and the light remains off. so now we're in a situation where we figure it's still probably best to wait until monday and fork over $450 (parts and labor) to have this maintenance done, since it's a common issue on e46's. but at the same time we both have interviews lined up in LA as well as the moving company taking our furniture across the country and trying to get to LA on time to hook up with them so that we don't have to pay extra $$$ for storage.

so what would you do if you were us? part of us wants to leave lincoln so we can get to LA and save the money that we'd be spending for food and hotel, as well as the $450 for getting our car serviced. the other part says that for peace of mind we should probably stick it out and have the car serviced because obviously the last thing we want is to be stranded in the middle of nowhere. having said that, the first guy in nyc replaced the mass air flow sensor and that didn't fix the issue. so who's to say this is going to fix it?

your thoughts?

lastly, we've had a cooling system overhaul as preventative maintenance; the filters changed as well as the oil and brake fluid. the only other thing i can think of that maybe in a one-in-a-million chance is worth mentioning: most gas stations that we've stopped at during our drive have 87, 89, and 93 octane; so we've been filling it with 93 and getting about 25mpg. this last tank we were able to fill it with 91 octane, which i know bmw recommends, and getting about 30mpg, as well as having the 'service engine soon' light turn off. any chance that the higher octane gas could cause these codes to come up?

sorry for the long post.

You are still a long, long way from LA. Are you going to worry about it all the way there? Not much to do in lincoln but there isn't much in between lincoln and denver and the cities are very spaced out on that side of the country. If it is running good, it is up to you, if it was something pretty serious you would think there would be other symptoms or issues.

Hope it all works out!! Good Luck.

yep, i'll probably worry at least a little all the way to LA. i think it's human nature to have at least a little worry when, as you said, we're in the midst of a drive where cities, and therefore help, are very spaced out on this side of the country. but i agree, if it were something serious i'd probably be having symptoms above and beyond a warning light showing up on the dash. and a warning light that decided to stop showing up on the dash out of nowhere.

7 hours to denver. 7 hours to st. george utah. and about 5 hours to LA. here's to hoping we make it with no more issues. thanks for replying.