[PeteF]

I installed a NAPA/Gates new OEM standard flow water pump ($28.99, made in China) and the overtemp problem is gone. I just drove around for about an hour on a very warm day here, and temps were very normal, 180-190 cruising and maybe 200 at stoplights. System holds pressure as it should and acts totally normal again. There was something about the hi-flow pump that was causing the loss of pressure and temp spikes. It could have been the pump combined with my underdrive pulleys that did it, but I am now satisfied. Thanks for all the good advice.