First off, if you are having problems getting to temperature, had you made all the best modifications that are passive modifications to the smoker? Assuming it is a charcoal smoker with a solid fire pan, similar to a Brinkmann vertical, there are a whole lot of modifications you can make.
Second, I modified a hibachi (old Japanese cast iron) to accept a blow dryer, it was too much and cracked the Hibachi. A leaf blower, no matter how slowly you run it, is going to be giving you a lot of air volume, I believe it could be unsafe. The smaller 2 to 3 cfm blowers are the way to go.
me: I don't drink anymore
Yelonutz: me either, but, then again, I don't drink any less