Just to clarify, you think it could be the Main Fuel Relay? Could you point me in the right direction as to where that's located? I've performed the tune as suggested above, but in doing so found that my tube seals on cylinder one are shot. So I need to get a gasket set and install before I do too much driving. So the jury is still out as to what the cause of my main problem is. Thanks for all of the suggestions.

 

OK, 101 here, but if it shuts off suddenly, with no sputtering, that would have to be electrical. If it were a fuel issue, it would sputter, almost certainly.

You didn't mention, but do you lose all electrical system - does the radio turn off, lights go out, etc?

Have you checked the computer for any codes? Do that and let us know what they are, if any. Here how - I stole from another forum:

Pull out the blue service connector from under the passenger side dash (close to the door). It may have black electrical tape covering it.

Using an unfolded metal paperclip (not plastic covered), connect the two holes of the connector ("jumping" the service connector)

Then turn the key to the II point, the one right before you actually turn the car on.

The Check Engine Light (commonly referred to as CEL) will flash. Long flashes are 10s, short flashes are 1s. Long pauses are breaks between codes. When the code repeats, that's all you get.