About a month ago I lost an injector.the 2 weeks later I lost another.the shop I brought it to said the common rail injectors only last about 100-120 thousand miles. I am over 130.so I replaced the other injectors.they said there is a filtration problem on the common rails.they put in a better canister filter and added an air dog filtration system.what does the air dog do?

 

Gives you more fuel, cleaner fuel and gets rid of your stock lift pump which is a weak link!
Be sure one of the filters is a 2 micron with that 300k is easy on your new injectors!