First post. I've searched high and low for symptoms exactly like mine with no luck. If there is a post you know if I'd love the link. Anyways, so I've got an '08 f250 that just recently developed a pretty odd idle. It happens only when idling in park or when my foot is on the brake while in drive or reverse. my truck typically idles in the range of 640-670 rpms but lately its been spiking up to around 800 rpms then down to less than 600 then back up again. I doesn't always do this but I can't seem to to find anyone who has this problem. Also, this problem only occurs when I'm at a stop light, idling backwards in reverse, or slowing to a stop. If I am driving at a normal speed with the RPM constant there is no stutter at all. I'm hoping i don't need injectors because I'd really rather not spend the money but any suggestions on a diagnosis would be great. I've got a mechanic that I trust here in Katy but he's expensive and I'd like to see what I may be able to do myself first.