2003 F-150 with slight misfire at idle

[roundhouse]

If you clean the butterfly or the mass air meter
Use ONLY the proper cleaner

Sold as throttle body cleaner
And
Mass air sensor cleaner

There is a coating on the butterfly blade
THe wrong solvent will remove it

 

[roundhouse]

Buy a code reader
They are cheap
And now you can get a cable that plugs to your smartphone Uses phone as code reader

 

[roundhouse]

I think you also have the year with the defective fuel pump controller on the frame above the spare tire
And also the fuel pump relay in the fusebox were known to go out

If it ever just stops running for no apparent reason
It will be one of those

 

[ZMBEKILR]

It sounds like another coil pack. When you change the plugs you ALWAYS loose at least 1 coil pack. I lost 2.

 

[brad sweet]

135k. No wires, has ignition coils.

notorious for boot rot arc to head cavity replace the boot or entire coil pack,if heavy misfire will set off OBD service light but a light miss wont

 

[sniper22]

If it were ignition or fuel related, it would give problem when under power and not intermittently. It's electrical (doubtful) or vacuum.

 

[harrycalahan]

It does sound like a dead spot on your tps. If you do pursue your egr, take it off and clean it first and check vacuum function before replacing.

 

[ShawnZR-1]

I've chased idle problems forever and 95% of the time it's a vacuum leak. Many Chevy's had intake gaskets leak, Chryslers have EGR problems and Fords have hoses that split at the most impossible points. Ether or starter spray is your friend (just be careful!).

 

[sniper22]

http://troubleshootmyvehicle.com/ford/4.6L-5.4L/troubleshooting-p0171-and-p0174-page-3

 

[AKguy]

I'm starting to think it might be a weak fuel pump. I've gotten a couple of jerky starts in the last week, and when first cranked, I can hear a sound coming from behind the cab that sounds like someone sipping liquid through a straw from a cup with almost nothing left in it.