My truck which i just bought now has 600 miles on it and has had a rough idle since i bought it feels like it has a slight miss. Also a small clunk in drive line between first and second around 15-25 mph. Also a slight vibration between 40-50mph. Brught to dealer at 400mi said all was okay. But they are going to be on lookout for updates and fixes. New to board any info would be appreciated! F150 Lariat 4x2 3.73LS Thanks..

 

I also have had a rough idle since truck was new. If I raise the idle very slightly with the pedal it gets smooth. Mine idles at about 550 rpm. Ford says they are going to have a software update to raise the idle but sofar nothing. I have 5.4 with 5100 miles. I also have the vibration problem under load between 45-60 mph. Screw with 3.73 posi axel. Some posts say its in the rear axel and some say the driveshaft. My dealer says it cant verify the problem.. I am the owner of an auto repair shop and had to have the service manager drive it for a few days to even get them to agree with the idle problem which is totally not acceptable. My 2001 F150 5.4 screw idled smooth and no had no driveline vibrations..

 

F150 Lariat 5.4 4x2 screw 3.73 LS production 09-2003

 

build date on mine is 1-14-04 also idles at 550rpm totally unacceptable,and it will not stand I will insist that it be taken care of. Could this be throttle body related or just software?

 

BTW , I also still own a 99 expedition 5.4 with 3.73 bought new!has 92k now, perfect idle perfect every thing!! never any problems at all...

 

I work on Volvo, Mercedes and BMW's at my shop and you can raise the idle with a software download on these vehicles.
Also we have had a lot of problems with the throttle units which are completely electronic with no mechanical cables on the Volvos and we disected them and found that there is a way to mechanically raise the idle by drilling out a plug and turning a factory preset throttle stop screw. I dont want to mess with my Ford because its under warranty and I should not have to at this point. Also note that the throttle response on the Mercedes is much faster than the Ford. If you push the pedal to the floor and back really fast on the Ford the engine won't even respond. The Mercedes and Volvo systems feel more like a cable system, although they are not. This also should be addresed.. Just my two cents worth.