You wrote
"The short story; ASR light and LIMP mode, ONLY occur when the outside temp is below 20 degrees F, and only in the first 5 minutes of driving, usually occurring when I come off the throttle, or hit the brakes. If I first let the car warm-up for 10 minutes, I can drive off with no problem."

Does make one think of temperature sensor / sender. Ah, but there's more than one.

Sorry to hear about the Air Pump, but better to have it checked before its clutch freezes and wipes out serpentine belt.

Here are two links regarding Air Pump Clutch that may save you some money.

w124 Smog Air Pump rebuild - ShopForum
http://www.peachparts.com/shopforum/showthread.php?t=186139&highlight=air+pump+clutch

94 E320 Air Pump Issues....What to do? - ShopForum
http://www.peachparts.com/shopforum/showthread.php?t=177803&highlight=air+pump+clutch

Doing a search on Air Pump Clutch will provide enough reading for today. Take note of post dates regarding parts prices.