i had the same problem, but my ventilation may have been better. ive got a dryer exhaust hole through my floor bringing fresh cold air in... i put my $25 Dollar General ocsillating heater ( seen em at BigLots too ) in front of that hole blowing the heat/fresh air into my small circulation fan. the combination produces no dry leaves, 2 fans blowing creates even more airflow, plus the temperature problem is solved.
the heater has a thermostat that works quite reliably, it oscillates, and you can turn the heat off and use the fan only. id recommend it for the price.