Hello, ive got a 96 f250 with a 460 that has lean codes 171 and 174. Ive done a bunch of troubleshooting and got it to where i can trigger the code whenever. So the CEL will stay off normal driving. But if i accelerate hard from a slow down or stop, it instantly triggers it. Ive changed all the o2 sensors, done new vaccum lines, replaced intake gaskets, MAF sensor...and so on. Nothing seems to get it completely fixed. Any ideas why it would trigger these codes only when hard accelerating? Thanks