Sounds like your linkage is sticking or binding. Get in under the air cleaner (remove it) and work the linkage by hand, see if you can feel any hard spots or binding. Check the link to the cruise actuator. This can bind and cause problems. The "thing" under the coolant resevoir is the coolant circulating pump. Comes on line when you ask for heat.. What you describe sounds normal..
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..