2005 FEH major engine vibration

I just bought a used 2005 Escape Hybrid. First several days its run good. Gas engine was a little bit rougher than my normal car but today it started making a major vibration through the whole vehicle. I turned it off when i got home and waited about thirty minutes and went to test it again. Same result electric motor quiet, minute or two of 30 mph driving and it started vibrating again. Any help would be greatly appreciated. I talked to the dealer I bought from and he thought it might be a rubber motormount? I am new to hybrids and the transmissions but it doesnt seem to be related to speed since the vibration continues for a few seconds after car is in park and shut off.