87 octane on a GST will cause big problems at WOT. If its floored im sure the thing is detnating and pulling timing. The plugs are prob a good Idea to do. And def get better gas in there too.

I assume the car is stock? you might not hear misfiring poping from the exhaust if it has stock exhaust. Is the check engine light on? Cause you could have autozone run the code and tell you what sensor is seeing the truble or if it is in fact a misfire on one or more cyl.

 

Thank you John...it's more like sputtering and it seems to be in cycles (?). Seems to be a little better today. My friend's multi meter indicated a misfire though, but I didn't realize that would sound different.

 

Thank you 93eclipse....as soon as I remembered I had put the lower octane gas in, I went down to Chevron and put in the 91 octane. I had 3/4 tank when I did that, so was only able to put in 1/4 tank of the higher octane. Then I put in the fuel system cleaner. My check engine light did come on, but this evening it has gone off.

 

I would say sputtering is a form of a misfire just not as strong. Detenation youll feel kinda hard and more if you floor it.

 

sounds like the lower octane fuel was paying its toll on you. that will do it. you can hardly accellerate with that octane being burned it burns to hot for your cars liking and is alittle to dirty lol

 

yea ive had issues with low octane fuel. Sunoco 87 octane is horrible!! it even made my N/A lebaron stall out.lol

 

the sunoco 94 was always good to me.

 

ive had best results with mobil 93.

 

When this first started, everytime I came to a stop, it felt like my car was going to die. Since putting 1/4 tank of 91 octane (from chevron) along with the cleaner in it, it doesn't feel like that anymore and acceleration is great!!!! The misfire diagnosis was from my friend's meter before I put the higher octane in. As soon as I can put more of the higher octane in, I will do so and just keep putting that in from now on. My owner's manual says that I should use 91, but "if premium grade unleaded gasoline is not available, unleaded gasoline having an octane rating of 87 may be used. However, the performance level may be reduced." I have always used 87 in it from the first day of buying my car new, but I really think I got hold of some 'bad' gas. But I PROMISE all of you to use 91 octane from now on!!!!!!!! LOL

 

the more i think about it the more it sounds like there was water in the gas. When my Lebaron (auto) got crappy gas with some water in it, it had similar issues esspecially upon deceleration (try having a car stall and loose power steering on a sharp turn in winter the 1st month you have your license.lol) so it makes sense that you never really had problems with 87 octane before up untill this past tank. Just stick with the 91 like you said and you will be golden