So after a decent drive when I get to a redlight/stopsign/etc the truck will idle rough and shake but giving it a little bit of gas (1k RPM) seems to smooth it out however it doesn't throw any codes or the CEL. The truck is a 2008 F150 with the 5.4 and 90k miles.
I've searched quite a bit on this issue and I can't seem to find any real fixes other than swap parts out until something works and I've heard everything from filters to cam phasers or low oil pressure (I will be taking it to the mechanic to check the oil pressure)
so far I've:
Replaced the air and fuel filters
Changed the oil and oil filter (synthetic and oem filter)
cleaned the MAF and cleaned the throttle body
also is the 2008 equipped with an IAC Valve because I've read that it wasn't and I can't seem to find the IAC if it is.
I had the same problem on my 2004 5.4L had a rough idle, also noticed a rattling noise coming from the right side hub while driving, and my cruise control would work on and off. Turned out it was a vacuum problem. I replaced the vacuum valve on the driver side fire wall (~15$) and the vacuum reservoir that sits behind the battery, its a little black box that holds pressure found one at a local junk yard for 10$. When you change this out I would also look at the connectors throughout the vacuum lines to make sure they aren't clogged up. After I did all that my rough idle disappeared, hub noises disappeared, and my cruise control worked whenever I needed it too.
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