just drove to reno with my check engine light on, pulls the hill fine and had power but was testing the mpg i know the code p0430 so before i left i cleared the codes and made it 200 miles with no light ? back at home in "stop and go" traffic the light comes back on in 30 miles ... does anyone know what would make it drive like a dream on the freeway but like crap in the city ? could it be a plugged cat or would it always throw a code if it was a cat issue ?

2005 f-150 xlt

 

Depends on what the problem was. You should've gotten the code before you cleared it.

 

. The code is and was p0430

 

Woops, you said that already. Sorry...

 

studleyjr, did you ever figure out your issue? I'm trying to run it down on my 05 as well.

 

Check to see that all spark plug wires are properly seated on both ends.
I had this error code and found the spark plug wire was loose on the coil side under the plastic cover and not readily visible after a battery change.