Why does my SUV shake when I drive at excessive speeds?

[Sarah]

I have a 2004 Isuzu rodeo with a little over 102,000 miles on it. I JUST got brand new tires in december-ish, and in January my car would shake when I hit 60-70 mph so i got my tires balanced. But even after having them balanced it still shakes. My check engine light is on but when they read my computer it's the catalytic converter code. Could it be my converter? Or something in the wheel area? Or engine?

I'm not entirely too smart when it comes to cars and I'm tired of getting scammed at mechanic shops and getting my car trash talked because its an Isuzu, lol.

Please help!
Honest answers please
I just had my spark plugs replaced in January, those are brand new as well. It was misfiring when my spark plugs were bad, but no it doesn't pull any which way. Gah I just know that tuneups for my car are almost 200$ and the catalytic converter is pricey too.

 

[Caine7SFG]

Have you had your tracking done? You might have your tyres balanced but you still need your tracking done..Does your car pull to one side itself is first signs..

Read here, no3 symptom..

http://voices.yahoo.com/the-3-primary-signs-car-needs-front-end-2873043.html

 

[nankumar]

Are you using snow tires? I believe it could be that as there is no snow on the ground which is what the tires are designed to grip on. Also due to it being the cold season, sometimes a little bit of ice could have gotten on your wheels which can throw the balance completely off with the smallest piece. Just check for debris or ice on or around your tire. Could be a suspension problem but I don't have much knowledge in that.

 

[Atmlmmmswmm]

maybe it's trying to warn you to slow down or die! idk?

 

[1562]

it could be ur converters not letting the exhaust out, but u should do a complete tune could be a misfire.