Unexplained high rpm

Hello, a little puzzled here. My ‘82 injected 308 is well maintained, in top shape, and has been running flawlessly. It’s been parked it in my garage for the last two weeks after a nice afternoon drive. Went out this evening to take it for a spin, and when it lit, the idle jumped immediately to a little over 4K on start up. The linkage is not binding, the throttle plate is not stuck open, can’t seem to find any hoses disconnected that would be creating a vacuum leak either. Just seems odd to go from running like a champ to this. Any ideas?
-Dave.

 

No, first thing I checked. Thanks!

 

Thanks, I’ll start there. I think I have a spare valve in my parts stash. Thanks for the help!

 

Unfortunately no, I won’t be able to make it.

 

Got it sorted. Couldn’t find any vacuum leaks, swapped out to my spare deceleration valve with no change. During all of this it did idle well at one point for 30 seconds or so then jumped back to around 3700 rpm. Looking at the motor scratching my head a little, I noticed that the engine wiring harness plug seemed to be slightly unplugged. Upon further inspection it indeed was. One of the side clips that hold it together had broken. I pushed the plug back into its receptacle and voila!! The car runs like a champ once again. I’ve secured it temporarily, but now have to source a new plug end somewhere. Thanks for your guys input. I appreciate it. Cheers, Dave.

 

Both the male and female parts of the plug assembly are a white / opaque color, 8 pin if I remember correctly. I’ll double check that when I go take a pic shortly. It’s located beside the ignition coils / top shock mount area. I’ll try and post a picture in a bit.