I am getting 7mpg with my ol' Dakota and it is killing me at the pump. It has 104,000 miles on it. Can it be the charcoal canister has
clogged up and needs to be replaced (possible along with the purge solenoid)? And maybe the carburetor needs to be re-built/
replaced?

If the carb is running rich then it needs rebuilt or replaced. If equipped with an oxygen sensor than it may need to be replaced, you may aslo have a clogged catalytic converter. Has it had a complete tuneup?

I wouldnt worry about this, if they were clogged and not working, this wouldnt cause it to be that bad. What kinda MPG were you getting before?