but I did put in the 1lb of corn sugar to the boil that come with the kit -
Only thing I can see is adding a lb of your priming sugar to the mix. That ferments totally as alcohol and may have added to your problem. I've fermented plenty of ales in the upper 70 degree range and never had an alcohol taste problem so I would say keep the priming sugar out of the mix next time.
Tough to do is you're making, say, a Belgian beer. I have the opposite experience from you...no problem with sugar, lots of problems with high fermentation temps.