I'm updating for my husband, as the Blazer is my truck.... We got it going and it seemed to run great until the running temp got to about 200 degrees. At stops, the idle would drop and the truck would vibrate. We got it home and disconnected the air cleaner system and took a look. Our neighbor pulled up and said to check the idle screw (which is supposedly un-adjustable) but is obviously not the original part. So, we got a torque screwdriver and upped the idle and although we haven't driven it yet (car repairs require beer!!) , it seems to be idling where it should be. I'm a bit skeptical that it is fixed, but hubby is bouncing off the wall in happiness. I hope this is the problem!!! Thanx so much BlazerLT for your advice. Appreciated SOOOOOOOOOO much!!!