Idle sticks at 2k when I slow to a stop

No electrical component in the throttle system (no throttle microswitch) and no mechanical parts in the ignition system on 1983 Mondial QV so your first focus has to be on the throttle plate mechanical system IMO - acc. pedal mechanism (carpet), throttle cable, throttle plate mechanism. Easy to do a visual to see if the throttle plate is more open when released slowly vs. when released quickly (just by looking at the throttle plate adjustment screw to see if the throttle plate is touching it or not).

 

With an all mechanical system it's straightforward to inspect and lubricate all the component parts. Also, check the return springs.

 

What they said ! Mechanical drag.

 

Throttle cables can fray. When they fray the strands bunch up and they can jam in the sheath. It can be intermittent. I had it happen with a car as I rolled to a light in traffic. 4000 rpm in neutral, shut the car off, worked throttle and restarted and it was “cured”. Was very relieved to get stopped before the rear of the car at the light.
Inspect it carefully.... or your nerve and wallet might NOT be so happy.

 

Frayed cables will eventually break. Then you walk home.
It's much easier to replace a cable while you still have the old one to "fish" the new one with.

 

Most likely a sticky throttle cable (been there), and they don't get better.

No way of lubricating them either (and a lot of them you are not supposed to lubricate anyway)

 

Check the number 3 fuel injector line. If it is not clocked properly then it can interfere with the throttle linkage. Dragging cable or linkage is also common as it gets colder out and the grease gets stiff..
The only other item I can think of is the fast idle valve on US vehicles which is closed through a thermal vacuum switch on the coolant expansion tank. a loss of vacuum or partial vacuum leak will cause that to partially open resulting in a above normal idle.

 

Check your floor mat resting against the throttle pedal. Or failing throttle cable.

 

I would agree on the cable - however if its fraying you should be able to feel this when you press the gas... ( engine off ) you can feel the resistance. My other guess ( this happened to me ) is that you have an air leak that is adding more air to the FI system plunger... so either at the cold start AAV or could be a cracked o ring in the throttle idle screw ( this one is a PITA ) I would also check all the electric connections under the trunk. finally you may just have cracked vacuum hoses... not sure where you are located but when the weather changed I would get some running issues due to old hoses. ( crakes open or close - heat or cold.)

 

Check the hose clamps under the plenum. A tail pointed up could make for interference.....

 

+1 for carpet (my TR does that on occasion).

My BB had a hanging throttle caused by a fraying cable. The cable manifested itself as an open throttle, i.e. when the cable intermittently sticks in the sheath, the car would rev to the moon in neutral, or just accelerate smartly in gear (it is fun when your Boxer becomes impatient just decides to do its own thing in traffic). A slightly elevated idle sounds more like carpet to me.

Did the car just get work done before the issue developed?