I have 98 f150 4x4 4.6 motor with 177,800 miles on it.The other day she bucked on me a few times would not go over 35- 40 mph, threw a cel got it to my mechanic , upon restarting no codes to take a snapshot all seemed fine, would not do it again so I took truck ran it for two days and on second day while idleing she died I restarted and she was doing same thing for a minute, cant figure it out cel will not stay on and no codes are being stored. Plugs and wires are new, new headgaskets and ex. manifolds, I have a cold air kit and mufflers thats it. Did notice strong smell at ex. of raw gas when this was happening.

 

Sounds to me like the cats have went south! Take it to a exhaust shop and have em check the cats

 

I was thinking of the cats, also maybe fuel pump and or filters?

 

The pump or filter wouldnt have anything to do with the exhaust gas that you smell. More than likely it is your cats, if it is replace them with so hi flow cats! Let us know what you find!