(2004 f150 fx4 5.4 90,722 newstle mc plugs)Ok First ? Is what do the 04+ f150 Idle at in GEAR at. Mine is idlein at the 2nd bar from the bottom. I know its low because when driving it and its rolling to a stop it nearly stalls it even affects the air conditioning. Ok So first I cleaned the throttle body. 2nd I dont believe its a cracked plug becasue it would be missin bad. Its not I did a supposed to be home test of the coils. I put the truck in park put on the e brake pull the plugins on the coils one by one and to my knowledge none of them really affected the idleing except for the first plug on the drivers side so I switched it with another, But to me it didn't follow the coil. I dont have a code reader Plus my check engine light is not on so I don't believe its threw any yet.Should I go down to the Autozone???? Plus yes I have did my searching of the post. I believe I am going to purchase the coils off eBay Global and then a extra because heard to many complaints of 1 out of 8 being bad. But my question is how would one know? and which one to switch? I just dont whatelse to do dont have the money for dealerships with insurance,gas,plus truck payments. Any ideal would be GREATLY APPRECIATED.

 

Also curious if it takes a few days for the ecu to relearn and to adjust to the plugs n coils and set its own idle????????

 

Have you checked for a vacuum leak yet?

 

Not yet wouldn't I hear it sucking if it was loosing vacuum? Where do I pull it from the throttle body???

 

You wouldn't necessarily hear it. Also, if you have access to a smoke machine I think that would make your life easier.

 

im pretty much screw. I guess ill just start with buying new coils and see if that solves the problem. I just wish sumone on here had experienced this already

 

Is it missing? If it were coils, you would have a miss. Have you cleaned the MAF? That has a direct affect on idle.

 

Blue Jay its not a miss because it doesn't stay with it throughout the rpm range. Its just when im in drive in neutral n park it idles at constant 8-900ish rpm. Just when Im rolling around without givin it any gas I have dynomax bullets with only two cats and I cant hear it.But im going to try cleanin it this afternoon.

 

menzies I just had this exact same problem after a plug change. I checked the vacuum lines with no problems. I had even changed the tps with no help. I then took the air intake boot and air filter housing off. Sprayed some sea foam deep creep into the throttle body and cleaned the maf sensor with maf cleaner. It now idles and runs better. I also cleaned my K&N air filter. I still don't feel I have the power that I did prior to the plug change but it is not missing. I think I have a passenger exhaust manifold issue now which may be affecting the O2 sensors and that spirals out of control.

 

Excellent.....but I hope you took your throttle body OFF the intake to clean it....leaving it on the intake and spraying the sea foam junk in there won't be good for the gaskets or the plastic intake....