Any proxy changer skips a proxy isn't working or slow?

Now I use SwitchProxy for Firefox .. and I need my power to turn intervals. I am a rookie at this, but its becoming quite difficult because most proxy lists match, dont work. So many proxy sites to subscribe, I tried to have a free trial from the beginning. You still get these proxy lists that dont work. So is there a program to jump on the servers Arent proxy not working and I have to switch manually every time? And can anyone give me some advice on proxy sites that offer really good, .. proxies daily work, I do subscribe to, if they are fast and hmm, it really works!

ProxyWay

switch proxy ( hide yourself online )