My 99 F-150 is throwing problem code P1131 and P1151 Says fuel mix lean, Vacuum leak, or misfire. While the truck is idling it runs rough but upon accelaration it runs good. Has anyone had these codes before and what was the fix. Thanks!

 

Check the elbows on the PCV. They are know to tear allowing a vacuum leak. If its ok on both ends of the hose check the MAF for a connection problem.