My car shakes and at times shuts off

The shaking and lack of power could very well be the engine misfiring. Keep in mind that is just a guess based on the scant info we have to go on. That could be caused by a faulty injector or faulty coil or...? But before you go and start throwing parts at it, a couple tests may be in order. First, make sure you are getting proper fuel pressure at the fuel rail. (your problem may be lack of fuel delivery and not injectors), you could also try a good injector cleaner. Second, test the ignition coils. You don't state what engine you have. 1.7L? Do you have the Coil-on-Plug (COP) ignition coils? http://troubleshootmyvehicle.com/honda/1.7L/how-to-test-the-ignition-coils-1 - so my advice to you is make every effort to know if the part is actually bad before replacing it.