Where does this vacuum hose attach?
I did the stupidest thing this morning. I was searching for a vacuum leak by spraying carb cleaner around the vacuum hoses without a fire extinguisher handy. Didn't find the vacuum leak, but started a fire on the back side of top of the engine which burnt a couple of minutes until I did get an extinguisher.
Now it idles at 700 drops to 600 then down to 400 then back up to 700. About a 4 second cycle. May or may not hesitate upon acceleration. Seems to run fine at all other speeds. Cannot find any burnt up wires, but this one vacuum hose was burnt in two. Cannot find where it goes. One end attaches to the tee in front of the driver near the hood. The other end doesn't attach to the connector clipped to the firewall center of the car near the top - it has all it's vacuum lines. The burnt end was lying on top of the engine near the PVC valve. See attached picture of hose and it's attachment point. The burnt end is above the top edge of the picture.
I was very lucky for being so naive.
My original problem was a PO171 and 174 codes. Looking for air intrusion. Guessing it ignited with a stray spark from the distributor area. Sprayed a little heavy back there without regard for the consequences.
If you have an idea where this goes I appreciate your help, if you think this is unrelated to the idle issue please advise. Thanks!