Fatalis, once you get done with the cook, let us know how it went.
Also, going forward, if we know what you're cooking on, what you're cooking etc...in the first post, we can be of more help, more quickly.
Generally, I do not like to use a load of old charcoal alone for a cook, they often look fine, but, have heated through in such a way, that they simply seem to burn out faster. Also, as was mentioned above, you will be better off with almost all of the charcoal in your cookers fire area, and just a few (10-12) briquettes lit fully. That gives you a more controlled fire. In my kettle, I know that 12 briquettes will give me a reliable 250F to 275F of heat. So I never need more than 12 lit, and a few pounds of fresh charcoal to back that up. I like to mix old charcoal briquettes into the new ones, that lets me be cheap, yet also, get a predictable burn.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
Whip It Off, Chambers!
"perhaps...but then again...maybe not..."