P1538 code ford f150?

If You're getting fault code P1538 (or P1537) on Your Ford F-150, it essentially means that the intake manifold runner control (IMRC) in bank 2 (and bank 1, for '37) is stuck open. The IMRC is a system that uses dual intake runners to provide each cylinder with adequate air. They're normally closed, but are opened if the driver is requesting additional power from the engine. When You're getting one of more of the above codes, it means that the system is not disengaging -- therefore, You'll always have that additional power. While this might sound attractive, it will lead to a decreased fuel economy and likely over-revving of Your engine at idle. This can usually be fixed by inspecting the vacuum hoses that attach to the IMRC.