I have a 2006 e350 5.4l that is skipping when at low Rpms. Mainly in o/d. It has a strong smell from exhaust. Have replaced all coil packs and plugs. It showing a to lean code and bank 1 and bank 2. Also a p0402 which is EGR. But I do not think this motor has EGR. Have been told it could be a vacuum leak, intake gasket, MAF, EGR, cad. Converter. Can anyone help to get closer to which one before I sink mire money into it. Thanks

 

there are a number of possiblities, but lets start with the simple stuff and start knocking down your list....
your local auto parts store has a special spray cleaner just for the MAF sensor. buy a can and use it according to its directions. the sensor isn't damaged or it would throw a code, but it may be dirty and inaccurate.

catalytic converter is unlikely, as it would throw a code of its own.

when you say it has a strong exhaust smell, can you clarify that a little - does it smell like a lawnmower engine which is running rich (unburned fuel smell), or something else?
if it does have that rich smell, then something is fooling the computer to say that its lean when its not, and the computer is responding by making it rich, or its misfiring on one or more cylinders, which would hopefully throw a misfire code, but fords are slow to throw a misfire code, which is why bad coils can be hard to find sometimes.

what brand of spark plugs and coils did you buy? some cheap aftermarket coils can be pretty bad.

 

I have had the MAF sprayed out still no difference the smell is a rich smell like unused fuel. The plugs are probably Bosch and had someone to put it all in so don't know what kind of coils was used. Hasn't pulled the first misfire code either. Have not had the injectors replace but have ran Lucas cleaner through it.

 

ok, a lean code combined with a rich smell is a misfire. the computer reads lean by the oxygen content of the exhaust, so one cylinder worth of unburned fuel/air means plenty of oxygen for the sensor to see, which tells it lean even though it isn't.
fords are VERY hesitant to throw a misfire code, which is a real blessing when its time for the emission test, but a curse when its time to diagnose something like this.

since you don't know what brand of coils he used, i would guess they were cheapos, and are somewhat likely to be your problem.

 

My brother-in-law with an '06 E350 5.4 had similar symptoms though I don't remember the specific intermittent codes. It turned out to be a section of wiring harness was in contact with the exhaust manifold and lost some insulation causing a coil to misfire.

Sixto
93 E150 Chateau 5.8 185K miles

 

Well come to find out plugs where not changed. Just coils. Attempted to change them my self but had 2 that was stuck so taking it to someone who knows how to get them out before j break will let you know I it solves the problem

 

good call not fighting them too hard yourself. last time i fought that on an econoline, it was about an hour of careful fighting with penetrating oils and a short breaker bar to run it back and forth the tiny bit it would move, finally got it out.
last time i fought that on a chevy, part of the head came out with the spark plug, it wasn't pretty

 

Took the truck to mechanic and they done a diagnostic test on it. Also put it in gear and held break and ran Rpms up to 3000. He told me I it ha a misfire than it would have done it. He said it pulled a lean code and catalytic code. That more than likely that mine catalytic converter was clogged. Does this sound right. Bc it seems more like a misfire to me.