i have a 97 sable that idles kinda rough and from 800 to about 1500 rpms it seems like it shakes... i bought the car for 100 bucks you get what you pay for and i have sank about 600 bucks into it. the check engine light is also on... it starts out solid and then after about 5 minutes of driving it starts flashing. i was looking for a little insight on these problemsany help would be greatly appreciated.