1994 Pontiac Grand Am Vibration and noise, as well as loss

Hello, my 94 Grand Am seems to be running a little weird now that winter is here. When it is cold, or if I haven't ran the car in awhile, the car doesn't seem to respond as well when I push the accelerator. It almost feels and sounds like a fuel issue, like its not combusting properly or something. It's hard to explain, but when I press the accelerator, it is noisier than usual, until it warms up, and it also feels sluggish, I would say, until it warms up. Any ideas? Also, since the day I bought the car, there is a slight whirring, and vibration whenever I get to a higher rate of speed. It is especially noticeable on the highway, and the noise and vibration is not constant, but it is in a pattern. It vibrates and makes noise for like a second, and then stops for a second and then does it and then stops. I was wondering if this could be the harmonic balancer. I read somewhere about torsional vibration or something like that. I would really appreciate any suggestions you could offer. Thanks!