I had the code for P0171 bank 1 lean , so i replaced front O2 sensor then cleaned back sensors , replaced spark plugs and coils , etc all of which it needed anyway and helped but I have a intermittent code for bank one and it will miss fire under the right load also . Sometimes runs perfect. anyway did a smoke test . 1 leak was easy around the bottom of the oil filler cap tube. Replaced O rings 2nd leak is around the EGR valve solenoid. Im thinking of just doing a block off plate between the EGR and the solenoid . Has anyone been able to link this small vacuum leak to driveability issues ? Anyone else with vacuum leak around EGR valve solenoid ?