Hope im posting in the right place if not i apologize,
i have a 2005 expedition 5.4 3v 165k i rebuilt transmission few months back. foward drum was busted i recently did timing all parts from ford, phasers and vvt solenoids and a high volume melling oil pump. The expedition runs great no problems exept sometimes my idle goes to 900 rpms and sometimes around 700+. on hot days if its running for over an hour i can hear some light knock ping like if it has bad gas, this happens when rpms is at 900 at idle. Also before and after transmission rebuilt and timing was done if i floor it there is barely any power it takes its sweet time to get up and going. No codes pop up. Any help is appreciated.

 

Could be your knock sensor is worn out if you have just run regular gas in it it’s whole life because they go out with age after having to be used all the time. If it is pinging like that that’s the only component that actually pings generally you would use minimum 89 octane in those things the SUV usually called for higher octane gas especially with age I have learned as a mechanic not to run regular gas as it gums up the tank and filter and lines sometimes. The knock sensor is easy to replace it’s 2 bolts and a wire so you probably wouldn’t need a mechanic to do it unless you run into difficulty trying to get it off or break it then it becomes a problem.