After 4 sets of heads and 2 full engine replacements, on this car, I think I have figured out how to fix this problem permanently! Thank GOD the car was a gift! Lord, knows I've spent more than it's worth on repairs! First, thing, Never use Dexcool III; or the Orange coolant, on a GM car! (it eats the gaskets!) You can use FULL strength antifreeze, not 50/50, the GREEN stuff! Just make your mix about; 58/42, that's a little more than half on the coolant side. Second, make sure All your gaskets have been replaced if Dexcool was EVER ran in your vehicle! Third, get a lower temp. thermostat; 180 degree or one for a high performance 3.4 engine, these can be difficult to find. Fourth,be sure water pump is new or equivalent; same goes for radiator and coolant tank. Fifth, the AC must be functional, or the fans won't work properly! It wont turn on fan til 195 degrees; and w/o AC, that's only 1 fan! Finally, Be sure to BLEED the air out of cooling system! If you don't the car's temp will 'flash' heat; it finds the air pocket and expands the H2o into steam, which builds massive pressure in the cooling system, that leads to blowing out a chunk of head gasket to relieve pressure. Because, the heads are aluminum, they Always have a tendency to warp, when the head gasket goes. which results in the pistons, potentially, hitting 1 or more of the valves! If you are replacing gaskets; Head, Intake, etc., be sure to use extra thick, tri-layered gaskets. They're new, and cost a little bit extra, but trust me they are worth EVERY penny! Since, my last engine install; 2000 Chevy Impala 3.4L, I followed each step to the word and have had No over heating problems, . . . YET! I also, live in Arizona, so this method has been tested in the most extreme condition available! Proven more than 100% The temp gauge never gets passed the half-way mark, in evening rush hour, on the I10, in Phoenix, in Aug., and the AC blasting at Max! Good luck, to anyone working through this nightmare, hopefully I can save you a few 1000 dollars for a nice stereo and speakers!