Hello. I have a '99 blazer. Sometimes while driving at about 60 mphit will start to run rough, almost like it is missing. When it starts doing this, it runs rough at idle too. Almost to the point where I think it is going to cut off, but so far it hasn't. When accelerating from stop signs or stop lights it is real hesitant.No check engine lights have come on at all. I don't think that it is a plug or wire problem because as stated earlier it only acts this way sometimes...most of the time it runs great. Any suggestions would be greatly appreciated. Thanks.

 

Sorta sounds like it is either choking on too much gas, OR starving for fuel. Too much fuel could be a leaking pressure regulator, bad injector(s). Starving for gas could be dying fuel pump. plugged injector(s), dirty fuel filter. Could also be a flaky sensor somewhere as well. Even though the CEL is not on, take it to AutoZone and have them run a scan for any stored codes.

 

Try some good fuel injection cleaner

 

I tookit by autozone tonight (monday). They scanned it for stored codes and there was none. While I was there I bought some fuel injecter cleaner. It acted fine while driving tonight. But it comes and goes for some reason. It has only happenedtwice in the past week. This weekend I will check a few more things. Thanks again for the suggestions.

 

Does it seem like it does this more so when it's very humid or raining outside??

 

The times I can recall it wasn't raining. It was however very humid. But most of our days are very humid around here. (eastern North Carolina)