Thanks for your response. The car idles normally for the 1st 5 minutes (approximately) with normal throttle response easily revs and then abbruptly jumps up to 1500 rpm (approximately) runs for a while then shuts off as though someone turned off the key. The car restarts immediately, runs for a minute more (approximately) then shuts off.

As I had mentioned the car returned to completely normal operation out of nowhere enabling me to get home from a few hundred miles away after it started to display these symptoms. Now it consistently acts up after a few minutes.