Got Fuel in you Coolant bottle? If so this maybe your problem. A "quick" test for this is to remove all 8 injectors and perform a coolant pressure test. With the coolant pressurized, look down each injector bore and see if it is leaking coolant. If any are leaking, PRAY it's one of the front four cyinders!

BTW, click on any of the below images for a larger version

Rusty Injector from Coolant / Fuel cross contamination

Injector_4_A.jpg Injector_4_B.jpg Injector_4_C.jpg

Coolant Pressure test, leak evidance in injector bore

Num2_Injector_Cup_A.jpg Num2_Injector_Cup_B.jpg Num2_Injector_Cup_C.jpg

Tooling and the removed cracked injector cup

Cup_RnR_Tooling.jpg Cup_Crack_A.jpg Cup_Crack_B.jpg Cup_Crack_C.jpg Cup_Crack_D.jpg