Recently, my 96 Civic Hatchback has been shaking intensely whenever I shift into first gear and in the past few days it's also been shuddering whenever I step on the gas. When I'm driving in 2nd or 3rd gear I can feel the car "tremble" when I step on the gas but then it disappears when I take my foot off the gas. On the highway when I hit around 50-55 MPH it starts shuddering violently when I step on the gas but stops and coasts smoothly when I let off the gas. It also seems like the car has no pickup no matter what gear I'm in. What could this be? Is it the engine mount? Is it something that needs to be fixed immediately? Is it safe to drive it like this? Thanks!