man i had this same problem with my 97 blazer 130 thousand miles. no clear item to call the culprit; weird problems stalling and re-starting. when i started to explain it to people i realized this is changing every day. i read here about the weird 97 ig switch (along with the 1000 other potential 3 letter culprits) and decided its a good place to start. if it doesnt solve the problem, well at least it will not cause any more issues.
i replaced the switch 90 bucks pep boys in stock. 2 hours of dash removal and 20 minutes of replacement time and it kicked right over. I WAS BLOWN AWAY... still cautious but it ran amazing well like new! tranny, shifting, even the service engine light went off... it had been blinking for 2 years. no one could ever diagnose it? code there one minute gone the next... yaaa! i can get smogged now and get registration finally stop looking in mirror.
thanks guys