This winter my car has been idling very high around 2k. I have a B18C. Once the engine temperatures get normal it still runs at 2k. Then it will go down to 1.5 and bounce back to 2k. It will do this a few times and then stay at normal around 1k. I dont know why this doing this could it be a leak in the intake manifold or maybe the computer going crazy?

Next question is the temp will go really high about 3/4 of the wat up then bounce back to normal.

Last is when my car is is in normal running temp I won't get heat. Hot air only comes out of the vents when I'm driving?

 

Could be two different problem or the same.

If you have a intake manifold leak you can take a can of WD40 or anthing flameable and spray around the areas where you suspect a leak. If the Car stumbles when you spray you found your leak.

The car overheating sounds like you dont have enough water in your radiator. You get an air bubble in the cooling system when the bubble reaches the temperature sensor the readings are inaccurate, when the bubble pushes through you will read correctly again. This is why it blows hot under acceleration.

You could have a blown head gasket, you either burning water or pushing air into the cooling system, this over pressurizes the cooling system and the water gets blown out.

when the car is running open the radiator, if you see bubbles then you have a blown head gasket. Also check your oil to see if its milky.