Rear engine mount changed and now weird vibration
 

Alright had my rear engine mount changed yesterday on my 92 Accord LX AT. Now I don't know if it is just me who has been driving on a bad mount for several years and not used to what a new one feels like, but the way my car drives just doesn't feel right to me. This only happens when in first gear and accelerating from a cold stop. Unlike before when accelerating the engine has a deeper sound and there is a very noticeable vibration felt through the steering and pedals, it almost feels like when there is a huge hole in the exhaust pipe right underneath the engine and you can feel it all through the front end. But as soon as the car picks up speed towards the end of the first gear and switches into second it is smooth sailing. And I tried it in reverse and nothing, only when it is in first and accelerating from a cold stop?

What is this? I had my mechanic check the mounts while he changed the rear hydraulic mount and he told me all the other mounts were in good condition. I know he told me he had removed the cross member,passenger side drive shaft, and battery box, could one of these things have not been fastened properly and cause this?

Maybe it's the alignment of the exhaust system? The engine moves around, especially under acceleration. The exhaust sytem moves down away from the floorpan, which stretches the exhaust hangers (rubber donuts).

Maybe the new mount positions the engine slightly different?? So you loosen the joints in the exhaust system & re-align things before tightening.