I have a 1988 V10 5.7 Blazer that started dying while driving or sitting still. I have seen many posts all over the net and now that I have finally fixed it, I wanted to get this data out asap.
At first I fell into the same trap that most fall into. I replaced........well the list of what I didn't replace is shorter than what I did replace. I'll just cut to the chase. It was the IAC valve. (idle air control). Its mounted on the right rear corner of the throttle body.
Most of the electronic items I replaced are from Standard Ignition and the IAC is as well. I got it from Rock Auto, it was half the price of the same part number that Oreillys had in stock.
Go online and search for "IAC re-learn procedure".
After you replace the part and perform the procedure, it is critical that you get the vehicle up to 40 mph for a couple of seconds. This will allow the IAC pintle to find the full closed position. At first I performed the re-learn but didn't get the truck up to 40 mph because I was on a residential street. The truck died mid test drive and again when I pulled into my driveway. I did the re-learn again and then went out of the neighborhood and got up to 40 mph. It hasn't died since. I took it for one more test drive before writing this just to be sure. It drove fine and didn't die. Its taken me a couple of years of being frustrated and only working on it because I thought it was a hopeless case. Now I can do some off-roading and enjoy my Blazer. I really hope that this helps someone who replaced everything including the cigarette lighter and still has this problem.
UPDATE !!!!!!!!!
Ive been trying to get back into this site to post an update but have not been able. Finally I was able to spend 45 minutes today and reset everything so I could do this. The solution to my engine dieing all the time was the damn ignition switch. The switch is the one located on top of the steering column under the dash. I didn't think it could be the problem because like everything else I had replaced it. I had finally had it and was going to sell my blazer. As a last ditch effort I decided to check the ignition switch. I loosened the two small bolts that hold it to the column and made sure it was installed correctly. Everything looked ok, but since I did what I did the truck hasn't shut off once. I even took it on a 30 mile off road trip and it functioned fine. If you've run out of things to check or replace, try this and maybe it will end your frustration.