"intake at 1/4 throttle" = pressing on the gas 1/4 way down, sucking more air in the intake

Get a friend to diagnose the problem. Put it in neutral, and let the friend give it some gas while you try to find out where it is coming from. If it is the intake, you can probably just fix it with some superglue or something :-p (ghetto fix). (intake should never get too hot anyway)

If you still cant' find the leak, try spraying some brake cleaner around. The RPM should jump up if that stuff find a way into the engine. Just don't aim cleaner sprayer at the air inlet :-p

Hope that helps..