Hi

Unless you have a really rotten hot end, there is no such thing as feeding to slowly. The extruder and hot end should be able to sit of hours with nothing moving through the system. If you have a really rotten hot end .... it's time to replace it. Simple check: The top of the hot end (where the filament feeds in) should be no more than warm to the touch when in operation. If you can't keep a finger on the top end of it for the count of five, it is to hot.

The simple check is still to tell the extruder to feed filament at the max speed setting. If that feeds fine for foot after foot of filament, the problem lies somewhere else. If it jams, swap out the filament and see if a different brand does the same thing. If two or three brands all do the same thing, your hot end thermistor may giving you bum data or your temperatures are simply set to low.

Bob