Intermittent high idle, any ideas?

Yes probably the cause. Small bore pcv vac hose generally connects to the intake manifold somewhere near the middle, often in a place where a strong light and a mirror is needed to see...

Yes I suggest the only other common issue is an engine vacuum leak, do a vacuum leak test with a can of car spray, spray around the intake manifold and vacuum hoses, if the idle changes while doing this zero in and that is the vacuum leak.

You can remove the iac sensor and clean the pintle and seat and reinstall, also clean the throttlebody plate. Check for vacuum leaks at the manifold. Try moving moving the idle air control sensor pintle out to (iac) contact the seat to close the idle gap. Reinstall and dont plug it in to the harness. See if it idles correctly, if your high idle is gone then, there is probably a dead spot in that sensor. If the idle stays high you will need a vacuum gauge to connect to the engine a get a reading to check engine idle vacuum, whic should be 15 to 21. Anything lower indicates a leak from intake areas such as injector o-rings bad vacuum tubes or hoses. Always prove things before replacing parts. Good luck

Spark Plugs have to be changed every 3 years
Front Oxygen Sensors changed every 100,000 miles
Can't have any Vacuum Leaks -- anywhere on the vehicle
Need to have it road tested with a Professional Scan Tool
& look at all data & get caught up on Preventative Maintenance
Very few people change motor oil 3 or 4 times a year, if at all,
and the Variable Cam Actuators fail, as a result,that & few other
things can cause rough running engine & resulting idle issues
It's well known that Ford COP Ignition Coils fail sometime in
every year of ownership

Check the vacuum hoses for leaks. Follow them around and make sure they're all connected and not worn out to where they had fallen off due to the hoses being old and worn out. Take some soapy water in a spray bottle and spray mist the intake and see if the idle changes. Check the big hose coming from the brake booster to the intake and make sure it's connected and in good shape. Basically check everything for vacuum leaks. It sounds like that's what you're issue is.

It can be issue with IAC( idle air control valve) causing the problem.

There are many other possibilities causing these idle issues.Engine idles rough.There are few help links with solutions to troubleshoot such idle issues.
I suggest you refer the link below and follow its troubleshooting details:------Click the link below:-----Bad miss at idle? http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html
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Stumbling and stalling at idle after engine rebuild? http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html

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1999 Ford F-150 Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html

--------- Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

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Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

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Cold start problem and vehicle shudder around 2500 to 3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html
---------- Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

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GMC Sonoma Stalls and idles low http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html
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GMC Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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1996 Camry intermittent engine failure while idle?

http://repairhelpcenter.blogspot.com/2011/10/1996-camry-intermittent-engine-failure.html

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Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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High Idle Problem
http://repairhelpcenter.blogspot.com/2012/10/high-idle-problem.html
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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed?

http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html

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High rpm in neutral? Inconsistant high RPM in neutral?

http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html

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Vehicle stumbling at idle and shows code 54?

http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html

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Rough idle, staling and Erratic shifting? http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html
-----------While stop engine idles like cylinder missing? http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------These details will help.Thanks.

may have knock off a vacuum hose. check the hoses in the area you were working.

this is usually a sign of a vacuum leak, if they took the intake off they probably had to take off more than 1 vacuum hose, make sure all the hoses on the intake are in good shape and connected tightly, a good way to find a vacuum leak is to take a can of brake cleaner and just spray the hoses (1 by 1 preferably) as you spray the hoses see if you notice the engine either idle higher or lower, if this happens while your spraying a hose this will be the hose with the leak

i would first check for a vacuum leak because this is considered a newer vehicle and does not have an idle screw, so I would get some "brake kleen" and mist it at each vacuum hose, if the idle changes then change that hose it means there is a leak, and that should sove your problem, if it doesnt , I would then check /replace the idle air control valve as this is the motor that controls the idle

dont replace you o2 sensor crimp off the hose going to the brake booster if the idle smooths out the booster is your vacuum leak so replace it.