so i have a 1999 f150 with 223k miles, 5.4 v8.. idles really low, (400-500)

it only idles rough, when i give it some gas it runs fine... if i just start it and dont give it gas, it stalls out immediately, but when i give it gas and kind of 'ease' it to about idle speed, it will idle at 400-500.

i took it to a mechanic last week, pulled some codes...

-cyl 3 misfire
-system running to lean
-crank shaft position sensor problem (something like that...)


he replaced the crank shaft position sensor but nothing changed. (of course)

i'm beginning to think its a vacuum leak, because of the system running too lean, but i'm not sure.. any help would be appreciated!

 

How olds fuel filter?...

Clean MAF..Air filter?..Clean the throttle body.. After you do all that unhook the battery for 15 mins...Then hook it back up... Let truck idle for 3 mins in park with ac off... Then idle for 3 mins in gear with ac off with foot on the brake... .. See if that helps you.. If you get a check engine light write down the codes and post them