Slow internet page loading and irratic download speeds.

My isp is cox.First i had low power levels,-15 downstream,48 upstream.They finally got my power levels respectable.Now my internet pages load slow,sometimes saying"page cannot load".My download speeds are all over the place.Sometimes i get 9MB download sometimes i get 2MB.I know about using various speedtest sites,trying to use the ones close to you.I pay for 9MB download and 1MB upload.Anyway i think my problem is with packet loss.I have done the virus scan,spyware,adaware,bypassing routers new cables,no splitters and new cable modems.No help. I have used ping plotter but cox says they don't trust it.So finally my question,what can i use to help me determine if i have packet loss.Sorry the post is so long.Thanks for any help you can give.

Well to make the long story short,cox has been out 6 times in the last 2 months.They hooked their laptop up outside at the cable box, bypassing everything from the box into the house and still acknowledged the problem.When i used ping plotter and sent the samples to their support site they said the problem was in the cox network.Hence cox saying when they run ping at the cmd prompt it shows no problems.