Engine shaking when in neutral?

My 2003 nissan altima was shaking the engine and when I go up the hill, the rpm reach 2500-3000 and the engine start shaking.?

• And doesn't have enough power to pull up the hill.

• Answer:

  It could be faulty spark plug ..or even 2 . I would first check spark plug wires if they are attached good or if it was raining a lot and you went through a lots of water some water might have gone into spark plug holes and now drives electricity onto engine instead of spark plugs if rubber spark plug covers are old and worn out ,