Help with some lean codes

[g556]

Been trying to fix up my 97 sport for a while now and keep getting p0171 and p0174 codes. I've replaced intake gaskets, tuned it up and recently discovered the pcv valve was disconnected. Even after reconnecting the pcv and checking the two vacuum lines coming off it the two codes still come up. Any help?

 

[koda2000]

Been trying to fix up my 97 sport for a while now and keep getting p0171 and p0174 codes. I've replaced intake gaskets, tuned it up and recently discovered the pcv valve was disconnected. Even after reconnecting the pcv and checking the two vacuum lines coming off it the two codes still come up. Any help?

a vacuum leak anywhere past the MAF will cause these codes. even in the power brake booster. disconnect and plug all vacuum lines and reconnect one at a time to narrow it down.

 

[2000StreetRod]

Lean condition procedure

Lean condition procedure

 

[joe doe]

Been trying to fix up my 97 sport for a while now and keep getting p0171 and p0174 codes. I've replaced intake gaskets, tuned it up and recently discovered the pcv valve was disconnected. Even after reconnecting the pcv and checking the two vacuum lines coming off it the two codes still come up. Any help?

did you replace these?

the small rubber pieces that go in the bottom of the upper plenum?if not ,thats your issue .replacing these have solved many a lean code issue around here .the parts right under the fel pro spacer

 

[jimbalaya]

fuel filter

I agree with folks here that have lots more experience than me that those two codes usually mean vacuum leak. nonetheless, i had both those codes last year and after cleaning the MAF, replacing the IAC and replacing the emissions canister solenoid [which had a hole in it from leaking battery directly above it], all with no luck, the thing that cleared the codes was replacing the fuel filter.