I'm new here and hoping for some additional input. I own a 2004 f-150 with a 5.4l, I recently installed a remanufactured engine. I've got about 150 mi. on the new motor,but whenever it reaches operating temp. it will only idle at about 500rpms. It threw a code saying mass air flow sensor was bad, so I replaced it. Then it threw another code saying camshaft position sensor was bad, so I replaced it. I still have the same problem, at operating temp it idles to low and will stumble and die. I did remove the computer during engine removal and installation. I was told it would have to relearn idle parameters, but its been 150 miles and this is becoming very frustrating. Any advice would be greatly appreciated.(sorry for the lengthy post)

 

You will have to reset the ECU again after changing the sensors. I would try that.

 

I've had the codes cleared after installing the new sensors, would that be the same? By reset the ecu do you mean disconnecting the battery or simething different?

 

Be sure its got over 3/4 tank of gas... Pull battery cables off and then turn head lights on.. Let sit for 15 mins... Shut headlights off.. Connect battery... Let idle for 3 mins in park with no ac on.. Then let idle in gear with foot on brake no ac on.. Then let idle in park with ac on ... Then let idle in hear with ac on for 3 mins

Each time be sure to let idle atleast 3 mins..
Also do this after its at normal operatiing temps

Sometimes when cooler outside it takes sometimes up to 3000 miles for it to start acting normal.. But non of this should throw a check engine light