My 2005 civic will not start if the engine is hot. Been having a little trouble with the temperature gauge shooting up and down, I replaced the rad cap and added antifreeze and the problem stopped. This morning I went to the store and when I came out it wouldn't start immediately. Had to wait about 35-40 minutes and it started right up, seems to be running fine once it starts, no noise, no smells. I'm stumped. Any help would be greatly appreciated, thanks.