The breaker for some of the outlets in my kitchen trips if I have too many items going at the same time. (Stove, oven, microwave, toaster) I think that it is a 15 amp breaker. Should I replace the breaker with one of the same rating or should I replace it with a 20 amp breaker.

 

You should do nothing with the breaker (except reset it when it trips). There is nothing wrong with it. It is doing it's job.

You need to stop running so many things at the same time, or run a new circuit or two.

 

The purpose of a breaker is to protect the wiring and receptacles inside your walls by tripping off if you try to use more power than your home's wiring can safely handle. In your kitchen now, you are trying to use more power than the wiring is rated for and the breaker is tripping off to prevent the wiring from overheating and catching fire. Do not increase the breaker size; it will create an unsafe situation.

The solution to your problem is to either use fewer appliances at any one time in the kitchen or to run an additional circuit or two to the kitchen to supply your appliances. For example today's code requires a minimum of (2) 20A circuits to kitchen countertops in new construction. With only (1) 15A circuit, your house is unable to supply the electrical demands of modern appliances.