While we're waiting for the weekend to come and go so I can tell you if any of your suggestions panned out re: my Ford Exploder, I bought a 2nd vehicle on Wednesday. '93 GMC 1500 Pickup. 173,000 approx.
I used to work @ AT&T and the majority of their fleet was GMC trucks. I have noticed an identical problem (that I had while @ ATT w/ their trucks) with my "new" one.
As you are driving (or parked) the odometer will wildly kick from 0-max multiple times and @ the same time all the lights on the dash go nuts.
There appears to be no rhyme or reason to the "glitch".
Lastly, when the battery light flashes in the cluster of flashing lights the engine begins to sound like it wants to stall yet once the battery light blinks out again the engine resumes its steady hum.
Dashboard cluster maybe?
Friday, April 30th, 2010 AT 11:56 AM