gsf150

Have a '99 F150, 5.4, 4x4 lariat, that idles low then dies after it rains, other times it starts right up, any help...?

wde3477

Check / clean the idle air bypass.

NGM

Check the connectors at the plugs make sure there is no moisture in there. Along with checking the TB and IAC

ro87f150

Check the vacuum hoses that goes off the air intake-valve covers on both sides.. and check to make sure that your pcv valve is in and not out. Check the vacuum lines for cracks.. make sure the intake is tightened and not loose..