Changed the plugs in the truck this weekend. Used NGk Iridium's. Now when the truck is at idle, the rpm's go up and down from about 500 to 1000. Not constantly but every 30 seconds or so. What do you guys think might be the problem. I posted in the maintainence section but thought this might be a better place. I am new to posting here but have been reading on here for several months.

 

I have that problem now. Did you solve your problem? and i if you did how?

 

reset your computer / disconnect battery ground / turn on head light switch for :15 minutes or so. that should do it.

 

Ford shop changed mine,sometime smooth as glass other time ruff idle. Just like yours about 500 to 1000 up and down idle Also seems like mine goes on high idle a lot on first start up. Taking mine back in the morning.
Shop said changing the plug out didn't have anything to do with it. Whats
everyone's thoughts on this? Sorry didn't mean to hijack your post