This has been going on for the last few weeks. Whenever I open up the throttle at around 3000-7000 RPM, I can hear and feel a rumble coming from under me. I have no idea what this could be, any clues?

 

check your exhaust, also check the bolts on the driveshaft flange where it meets the rear axle and the CV axle flange bolts. I've heard of these coming loose.

 

you know i currently have the same proplem with my car. it started ever since i lowered it. but to me it's some kind of vibration comming from under the car. i don't know what it is yet. i checked an double checked all the bolts to see if it's all tight and balanced the tires too so far no luck. i'll keep you posted if anything.