The car starts to overheat on the temp gauge when it reaches over 2.5k RPM. What kind of problem could this be?

 

Blown headgasket and/or weak/stretched cylinder head bolts. When pressure is put into the cylinder it may be slightly lifting the cylinder head which allows combustion to pass into the cooling system. In effect, this super-heats the water and causes a spike in temperature. Once you let off the head sits back down and the system cools off. This is my best guess without knowing anything else about your car and its set-up. Hope this helps.

 

sounds like a head gasket problem just like way2qik said where are you located.

 

Have you checked your coolant level?

 

Ah it might be the head gasket, one day when I was parked it was leaking some kind of oil mixture with coolant, but then I wouldn't know how to confirm this. But then again I hit a bump and somehow when I bumped the front bumper I think I cracked the radiator because the coolant leaks out every time I put new coolant in. I live on the east coast, US, in MA.

 

When I start the car the intake manifold also gets super heated as well, and sizzles...

 

So your coolant leaks out as soon as you put new coolant in? Seems pretty obvious that you need to fix your coolant leak. The fact that you are asking why your car overheats, when you know that coolant is leaking out of your radiator......you better take your car to some professionals.

 

Well I was wondering if maybe it was just more than a radiator problem, I am inexperienced in automotive repairs but after reading around and getting some help from here I may have an idea of what kind of problems will need fixing and will have a professional take a look. Thanks for the input though.

 

cooling system works under pressure. the pressure on the water raises the boiling point. with a rad leak the system will never pressurize.

 

Ah that makes sense, now I understand how the leak affects it much more than I thought, so the head gaskets might still be OK.

 

Another problem I have is that when I start it up if I don't give it a little gas it will stall out until I wait a few minutes, and also idles strangely; this is especially worse in the winter.