Driving with lean trouble codes

[99f150xlt4.2]

The CEL light came on for me the other day and low and behold p0171 and p0174 codes came up...the search begins. I have a few places I'm going to start looking for a vacuum leak but my question is; over the next few days as I try to locate the leak, is it still okay to drive the truck even though it's running lean? If I don't find the leak right away the last thing I want to do is burn a valve or something. Any thoughts would be appreciated. My truck is a 99f150 4.2l.

[projectSHO89]

Check the PCV valve hose elbow at the firewall.

Won't hurt the engine to drive it that way.

Steve

[04f150stx]

I haven't been able to find the problem on mine which started 8 months ago so I just keep driving it. No problems so far.

[stackin123]

i have the same codes thrown on my truck as well. Check to see if you have any exhaust leaks...it could be a vacumm but i tore my truck aprt and kno vaccum leak i had cracked the exhaust manifolds therefore i was sucking in air and the 02's were reading lean...what your computer does is recalibrates and thinks to run rick so you dump more fuel...in effect your motor wont get ruined or burn a vlave your just probably going thru alotta gas...