'Potentiometer reading between 14 & 18 pins on the potentiometer 4890 ohms non-adjustable, and about 50ohms over spec: enough to replace?'
This is about 1% of spec - I'd say damn good.
'Readings between 14 & 17 pins: 750 at rest, 5670 at full deflection, as high as 5690 dear full deflection. Enough to replace?'
I don't know what they should be, but typically a pot's resistance may decrease at the full stop compared to at the end of the resistance element. Not likely a problem. Pot failure mode is usually an intermittant internal connection, a worn wiper (erratic reading at spots), or an open terminal. It is rare to get a significant change in resistance due to failure.
'If I don't see any increase in current for fairly large movements of the throttle, is the computer
ignoring the potentimeter, or is this likely a potentiometer problem?'
Again, I don't know what is happening. But, to maintain precision, it is typical for a monitoring circuit to use a current source to deliver a constant, precise current to the pot - then monitor the voltage change as the resistance varies.
Hope this helps, since I am a neophyte with CIS, but involved with electronic control systems for decades.