My grand marquis is overheating and smoke is coming from the area where the radiator hose plugs in the top of engine?

...wow...what's left of your motor? is there still compression? are you getting oil in the water jacket? coolant in the oil? what's the dipstick look like? Do you have a cracked block, or broken heads...or simply blown head gasket? Did you not replace the lost coolant when you started smelling popcorn?

did you look at your oil? Does it smell burnt? have you considered an oil change?

Could it be coolant evaporating? A cracked intake perhaps?

You probably didn't get the intake manifold seated correctly and you're sucking air, losing vacuum and leaking fluids from the gaskets. The 5.0L intakes have a tendency to leak, the gaskets have to be just right and should be glued in place before setting down the intake or they will move and cause leaks, more than likely coolant leaks. you can't move the manifold once you set it down on the engine or you will end up moving the gaskets out of place. Try to look directly under the front of the intake first and see if it's looking green(color of anti freeze), If so, you'll have to remove everything again and start over with probably another new set of new gaskets. Don't over tighten the intake bolts either. Use a torque wrench, if you don't have one, you can usually rent one from autozone or advance auto for free. Get a chiltons repair manual for the manifold bolt torque specs. Good Luck, Kenny/MrBlueOval

Will a 1997 Mercury grand marquis cylinder head interchange with a 2005 Mercury grand marquis?