The coils are sensitive on those carts in that you need one with pretty specific internal resistance as described here:
http://www.buggiesgonewild.com/gas-c...formation.html
That being said, it's not often that the coil goes bad as they are normally rugged. It's usually a less rugged portion of the ignition circuit that goes bad like the module. For sure, though, there are dozens of coils listed in that link. You may want to try to switch things up.