The car vibrates when accelerating from 30-45 mph from under the engine..

You state the engine does not vibrate and a standstill or when revving the engine. What about when you put it in gear, hold your brake pedal down firmly and then rev the engine? If it happens then, it would indicate transmission or engine mounts. If not, it could be multiple items from a misfire to emission issues. Is your check engine light on? The best advise is for you to bring it in and we can diagnose the issue. Our diagnostic fee is $99 and for that we will tell you what the problem is and what it will cost to fix it. If you approve our recommendations, we will waive half of the diagnostic fee. Let us know if we can help you out.