Just picked up a 1994 Civic for a beater. Only problem is everytime Im on the highway the car starts shaking. It starts at about 50 miles an hour and only when Im on the gas. As soon as I let off the gas it stops. Does anyone have any idea what it could be? My friend thinks its the tranny my other friend says its the tires need balancing, blah blah blah.....Its just my beater for work but any help diagnosing it would be great..thanks

 

If tires were out of balance I don't think the shake would go away when you ease off the gas.