need your opinion on computer codes

[1968k10blue]

I have a 99 silverado With the the 4.3 and I keep getting codes, don't remember the precise number off hand but I get a code for "fuel trim system too lean" on both banks, it has been a while since I actually read the codes but at the time those were the only codes to show up. The truck has just under 80000 miles on it. Possible causes?

[1968k10blue]

So, I got a cheap scanner that I left plugged in while driving, and as soon as the check engine light appears it always shows the po174 code which is fuel trim system too lean bank 2, but if I leave it longer and not clear my codes the bank 1 code comes up (po170 or 1 I can't remember off hand) all my o2 sensors are good, so I think I am looking at a vaccum leak of some kind, tonight I will go at it with a bottle of carb cleaner to see if I can find it.

[1968k10blue]

Figured out the problem, it was a bad MAF so 85 bucks later and the check engine light that was on for over 2 years was gone! And now my truck will stop trying to kill me... Next up is figuring what's up with my ABS