Mitsubishi Repair: 02 Mitsubishi Lancer OZ, mitsubishi lancer, computer test

Question
Twice now I have been on the interstate and my car starts to violently shake.  Its random when it happens.  If I turn my car off for about 20 minutes its fine again.  I have had 2 diagnostics tests done on it and there was nothing.  My service engine light does not come on. They checked the tires, motor mount, axles and numerous other things and found nothing.  Any ideas?

Answer
I would go for HOT plugs. I would say replace the plugs first with standard stock spark plugs. If this does not work then I would start looking at the fuel system, Maybe your MFI sensor, sometimes it goes bad and you don't even know it and this sensor will not show up on a computer test. When either one of these happens then it will not fire properly and the will do random misfires. Please let me know if this helps,thanks again Kevin.