Recently did an engine swap on my '94 Celica GT and I've been experiencing an odd phenomenon. I recently topped the coolant, but after driving the car and I shut it off, I turn the key over just right before engaging the clutch and starter (gauges start reading) and my temp gauge BURIES into H past red and once, the car had difficulty starting kind of sputtering... so once I do get it started, I rev it a few time and it goes back down to operable temperature (midway) any idea? Also, I notice that my reservoir boils and sometimes will boil over. I can't seem to find the culprit... any ideas to look into?

Thanks,
Brandon