Sometimes I can smell hot antifreeze soon after start up on my van, in the interior.

it must be coming through the heater vents.

Any one ever have this?

It is not often, or all the time, just on random occasion............

I thought heater core, but usaully they go, and continue to leak.

 

Did ya thoroughly check around the cabin (floor, etc.) for wet spots? Also, get a magic marker and mark the fluid level (engine compartment) after it sits overnight. Then each morning (after it sits overnight and before you start it) check to see if you are losing fluid.