I recently drove my rx8 04 to lake george over the weekend and my and my friend were pushing between 90-100 on a straight road for about 20 miles.when I slowed down for a toll my car shut off, no warning needle didn't even indicate that it over heated. The fans stayed in for like 10 min and then car finally turned on.
Drove about another 20 miles a little slower and when I stopped for gas car shut off and again no indication that it overheated no smoke no coolant leaking just shut off. After 10 mins. Car started and I hit the road again. After about 10 miles going slower at 65mph tempeture gauged spiked and my car started making a gargling noise like it had a straight pipe so i pulled over to the side and the coolant was spewing out threw the little hose connected on the coolant resevoir . took to local shop compression test read 30 on one side car only started again for 10 seconds and shuts off After shaking. Idk what to do now.I just rebuilt the motor last year . warped intake, blown apex seal, coolant seal?

 

It sounds like a coolant seal. If you can get it to idle or run at all, check if there are bubbles in the overflow tank. If not that, pull the plugs and look for green/white crust on them.

When you rebuilt the engine, did you have it done or do it yourself? What coolant seals were used?