The car: 82 245, K-jet, white distributor cap, 163K.

The problem: once the engine has warmed up it tends to develop an irratic idle. Whenever I depress the clutch to come to a stop, the engine plummets to nearly zero rpms (really, it almost stalls!). It shakes pretty good and emits a knocking sound. Then it bounces right back and settles at a steady idle, but only for 3 or 4 seconds, then it dips back down, shakes, knocks, and comes back. This pattern repeats whenever the car is idling.

No problem when driving, only when idling.

Possibilities:
1. Ignition: I have had some connection problems where the harness plugs into the module. It doesn't have any of those sleeves installed, but I'd like to get some. It has the original wiring harness. But if it was a connection like this, wouldn't the car sometimes completely stall or sometimes display these symptoms while driving? And why would it only happen when warm?

2. Vacuum. I know next to nothing about vacuum, so I need an education on the subject. Should I spray the hoses with carb cleaner--that's what I've heard?

3. Dirty components? Either the throttle body or something in the idle system? (I'm not sure how the idle system works in this car either)

Your suggestions are greatly appreciated--they've been so helpful in the past.