when im driving my car is smooth but after about 5 minutes of highway driving my car all of a sudden just has this pretty harsh vibration. then ill go into a store or somthing and hit the highway again, its fine until 5 minutes later out of nowere theres the vibration i need help cause idk what it is. my car has 240 000 miles on it but this just started out of no were. i was thinkin it was something internal because it seems to be as soon as it hits about 190 degrees it starts

 

hmm, you might be on to something, sounds like it's after the car is up to temp.
Any modifications to the car? Sounds like you swapped to a manual.
Any mods done recently? Long time ago?

When it's shaking on the highway, if you put it in neutral is it still shaking?
rev it when stopped, do you still get the shake?
in one gear or another?

 

well everything is all stock besides the swap... i just put a cf dual friction in about to months ago but this just started maybe 1 week ago before it was fine.. the previous owner had a wreck and it hit the quarter but the frame is not bent. and i didnt have a problem before i didnt see if puttin it in nuetral would make it quit but i will tommarow some people said it sounded like one of my cyclinders wasnt getteing spark? idk thanks