1990 Nissan Maxima

I have an automatic, 1990 Nisssan Maxima, it has about 127 thousand miles, it has a rough start in the morning but that's because my flywheel is broken, the mechaning told me not to fix it because it was going to cost more for the repair than for the car itself, the problem is that when I switch it into gear, the car jumps, and last night when I was trying to park it, I put my car in reverse and I felt it shaking and I heard like metal clinging, like something was loose. I sounded like a piece of metal was moving underneath my car, and I heard it on the driver's side. I swtich it from drive into reverse a couple of times just to see if I can hear it again and it did it like two times after that. This morning I drove it and when you switch it into gear it still jumps a little but I couldn't hear the metal clinging anymore. Also the speedometer sometimes doesn't work. Does anyone have an idea of what can it be? Is it going to cost too much to fix it?