RequestThrottled is an Amazon way of avoiding making too many requests to your API in a short period of time (according to them, every 1 second, only 1 request is possible). It is a practice used to prevent DDOS attacks, for example, when requested many times the API will start denying access to requests that use the same network.
According to Amazon itself:
If your application is trying to submit requests that exceed the
maximum request for your account, you may receive error messages from
Product Advertising API. The request limit for each account is
based on revenue performance. Each account used to access
the Product Advertising API is allowed an initial usage limit of 1
request per second *. Each account will receive an additional 1 request
per second (up to a maximum of 10) for every $ 4,600 of shipped item
revenue driven in a 30-day trailing period (about $ 0.11 per minute).
Apparently the only way around this problem is to increase sales. I can not tell if Amazon accepts another way to increase the amount of request.
Reference