My blazer I've had for six months at first it was great. It had a tiny misfire but it never had any major complications. Three months ago it started to periodically turn off while driving. I changed the EGR valve and the fuel filter and it was fine. I did the tune up about five months ago. And it also got a fuel pump about 9 months ago.. It still has the little misfire but idk what to do to fix it. I've run injector cleaner through it as well as a fuel system cleaner it didn't help. I don't know what is wrong. I also replaced the starter so that's still good. It doesn't have a check engine light. Anyone have any ideas?

 

Have you done a compression test?

When was the last time you replaced the ignition coil?