OK heres the deal i have an 07 F150 with the 4.2 and it is pinging and idleing rough.
At around 35,000 miles the check engine light went on and it was throwing a code that i narrowed down to the catalytic converter or O2 sensor, well it was still under warranty and i should have taken care of it but i didn't and at around 43,000 miles the check engine light went away and now at 48,000 it has started idleing rough and pinging at higher rpms. The truck is still under emissions warranty but there is no check engine light so i don't know if the dealer will do anything or not and i don't wanna have to pay a ton of money.

So what would some of you guys do???

 

If you trust your dealer, I'd take it back and explain the CEL came on, went off and the truck is running poorly.
They could check it and give you an assessment before any repair work took place.

I do not know for a fact, but I have been told dealer service departments actually want warranty work because it helps their bottom line.

 

OK cool i was planning on doing it this week thank you very much!