91 accord probs...

I was looking for some help with my 91 accord...ok first sometimes it starts...sometimes it doesnt, it turns over, engine starts for about a second then the engine just dies...the car was sitting for quite some time before i actually got it, maybe thats why? Then when I put the car in reverse and the car jerks pretty hard, and when im idle it shakes alot...can anyone help and tell me whats wrong and how to fix it? thanks...

Iwould start with the cheap things first, i.e. spark plugs, check air filter. Do you have a check engine light? Motor mounts will cause the engine to shake. So many things to consider, but spark plugs might be the cheapest to start with.