A short term/quick fix to get you through this heat, I would suggest removing the thermostat so you get continuous coolant flow. I'm not familiar w/ 8 cyl setups but if your a/c condenser is in front of your rad,(like all cars I've seen) might it be clogged w/debris? or have a buncha bent over fins which would block your airflow? Also some fans are reversible, might they be spinning backwards ? that's my $0.02............ good luck, let us know howya makeout........E.