I have an '04 f150 4x4 5.4L lariat new body style, I purchased it a few months ago. (I had an '03 f150 4x4 5.4L lariat that Im compairing the new one to) It seems like this 04 doesnt want to get up and go,(like the '03 did) best way to describe it is like having a potato stuck in the tail pipe. then after driving it for a few weeks I got CEL I think it was P0140, the day I was going to change bank 1&2 sensors 2, the code went away. so I didnt change them. I instead opted to change the plugs (all plugs came out fine) now I notice a fuel smell when I let off the accelerator,(not sure if I smelled it before) its like a boat exhaust smell- not a raw fuel smell. I am wondering if all these things add up to a clogged or partialy clogged cat or just a bad o2 sensor, I dont to spent $100+ for the rear two o2 sensors and still have the same problems, nor do I want to replace the cats and find out it was the o2 sensors all along. when I smell it in the cab, I do not smell it anywhere else, like: under the hood, or any where else under the truck, nor do I see a leak under the truck.

 

Check the torque on the plugs, make sure it's high enough. Could also be plugged cats, but you should smell that just about all of the time she's running.

 

I will monitor the smell and see if constant or sporadic

 

Seems constant, I notice it more when I slow down or come to a stop.

 

Likely a plugged cat.
There is a national 8yr/80k mile warranty on those buggers. How many miles on the truck?

 

Almost 130,000, what do those cost to replace?

 

Replacement from the dealer is pretty pricey...too much $$$ in my opinion. Magnaflow (the exhaust company) has some general replacement cats that are pretty affordable, relatively speaking. I'd look into those.

 

id also go with a loose spark plug.my dads truck had a bad gas smell under the hood and we found a loose plug.also had a cat melt down on it also a few months later.the top side of the brick looked ok.when i cut a square out of it in the middle the thing looked like a volcano.he was exsperiancing a major lose of power.it sounded like a 4 barrel carb getting the seconderies opened up.

 

Im-Tech
Was you're dads truck with the bad cat only losing power at 1500-2000 rpm? Also did it turn on the cel? My truck has loss of power at those rpm and has the 4 barrel sound only when warm and when it's losing power. Just curious it might help me if so. Thanks

 

drop the exhaust down and see if it runs better.i had a cat code for the side that was giving me problems