SEVERE ENGINE ROUGHNESS
 

My 89 gt runs quite well (although not completely smooth) up to about 4800 rpm, then all hell breaks loose. there is huge vibration throught the car and engine abave 5000rpm. It seems to be mechanical in nature, like the timing was completely off. there was also the smell of un-burned fuel although i'm not sure this is related. It's also a little jerky at lower rpms. 1000-2000.
Anybody out there have any ideas?
Cheers!!

I had a similar with my 88 S4. Replaced bad motor mounts and all's well in rev land.