s13erm

iTrader: (3)

how are you verifying the thermostats are good? Doubt all 4 would be bad, but putting them in boiling water and watching them open would give you visual proof.
Are you getting any mixture, oil & coolant? White smoke? If you have access to a combustion leak detector that's another option, or just run a compression test.
Make sure and bleed the system well. Jack the front of the car as high as you can, and let it idle a good 30-45 min...

Felts

iTrader: (1)

just from the chance that 4 different thermostats and 1 of them being a mishomoto lower temp thermostat all giving the exact same symptoms i think is good enough to rule out the thermostats. Not only that but the fact that the temperature is perfect at idle for 30 minutes. as soon as you rev the engine the temperature climbs in about a second and as soon as you let off the throttle the temperature drops immediately back to normal temp. I havent had a chance to do a leak down test or have another shop do a diagnosis on it yet but pretty certain its the exhaust gases getting in the coolant system. there isnt oil in the coolant but you dont always have oil in the coolant with a blown head gasket. I also dont have white smoke. I know this is all a guess but im pretty certain its the headgasket related