I have a 98 4.6 4wd standard trans truck. I have just thrown a code saying that both banks are running lean. I know this is usually a vaccum problem but i cannot find a leak. What are some common places for leaks? I have searched high and low and have come up empty. Another issue i am having is a rattle when under heavy acceleration. Does anyone have any suggestions or ideas. Thanks in advance.

Austin

 

There is a good chance that this is not a leak but an O2 sensor, Just had the exact thing happen on my truck and it was shaking like a wet dog when i got on it. It amounted to one code showing the truck was running lean. While waiting on a fuel pump I drove it some more and it threw a misfire in cylinder 3. Total damage was 1 coil 8 plugs (safe side and all that ) and it still threw the lean code so both o2 sensors later and its running like a champ so possibly look into your sensors and maybe even have your coils run on a scanner to see if they need a swap.