I recently had these problems with mt '96 S-10 Blazer. I found out that my answer was a fuel pressure regulator, but my first mistake was taking my Blazer to the wrong mechanic. After a day of diagnostics this mechanic did a fuel injection cleaning and a themostat replacement. This did nothing, then he replaced the plugs, plug wires, cap and rotor.
When I went to pick up my Blazer I was hit with a bill of over $600. I left the shop only to return it the next day with the same problem. So I left it with him for 2 more days while he tried to find out what was going on. After taking it from his shop after a total of 10 days, I took it to another mechanic recommended by a friend. I told the mechanic that I was having difficulty starting the car and that the idle was rough, he said it sounds like I needed to replace the fuel pressure regulator. That was it and now it run great.
