with the negative cable off the batter cannot charge the coil its an incomplete circuit therefore if it died you would know that you had a bad alternator

 

even though the coil is grounded through the TFI, and the alt is grounded to the engine....

 

im talkin about the battery directly charging the coil it wont work without the cable

 

right so that would be a battery issue not alt.

 

i was saying if there was a problem with the alternator and you disconnect the battery you have disconnect what is charging the coil which makes no spark and your engine will die thats only for an alternator problem

 

theoretically disconnecting either cable on a system that is grounded to the battery will kill it. but on the EEC system, disconnecting the negative cable will not kill the car. most alternator's put out 10 volts +/- when they begin to die. although this is considered a discharge, it is still a postive 10 volts after the battery has drained that far.

 

Or you could just use a volt meter

 

+1 on the volt meter, so much easier.

I have had similar problems twice before in the past. I found both times that some wires had goten too close to heat (heads or exhaust) and would intermitantly ground out. That's the only thing I can think that fits all your symptons.