When I'm driving on the highway the car will randomly start to vibrate, if i give it more gas then it will come out of it... usually when im doing about 80. but sometimes if im doing 40 as well.... even when i have it on cruise control it will just start to shake for like 5-10 seconds then come out of it..

its a 96 accord, still have 3 months warranty on it but have yet to get it inspected what can i tell the mechanic at the inspection place to check for? any ideas what it could be???