Ok so I have the 2009 f150 4.6l 2wd. Have random misfire codes. Horrid idle. I replaced all of the spark plugs, coil packs, and even the injectors on 1/3/4. Still codes nothing is better. I'm thinking maybe an intake manifold leak,? I see no real signs but I do hear that little pop pop pop. Now I have a gasket kit for it but I see you can order complete manifold kits with thermostat and gaskets on amazon for like 60 bucks more. The issue is I see none that fit my truck. Is it the same as the mustang? Hate to blow more cash as its adding up. Anything else it could be? Sorry if there are typos on a tablet. Thanks

 

Spray carb cleaner around the intake manifold and see if it idles better. If it doesn't, it probably isn't the issue.

 

Also, use a noid light to see if PCM is firing injectors and coils...

 

Thanks for info. I changed intake gasket it wAs damaged and helped a lot. But still had issues with cyl 3 1 and 4 cleared up. Turns out to be cyl 3 had blown a plug 8 months ago well the insert and plughave melted and I need a new head. Of course I have the stupid motor nobody makes parts for so a new head at ford is 1400. Or i get a complete crate rebuilt engine for 2900 through ford. As im up to 140k and have a brand new tranny and rear end I think I just might opt for the new engine. They claim they have updated heads that dont have the blown plug issue.... we will see. Thanks for the help!

 

Seems to me that smart says, get the new engine if you plan to keep the truck.