Sounds to me like there's coolant coming out of the throttle body, and pooling on the air cleaner from reversion. Intake gasket leak, maybe head gasket or cracked casting.
"I" would want to do a cranking compression test; and maybe a leakdown test on all six before opening the engine up for anything except spark plug removal. Add in a cooling system pressure test, too. All the tools except the air compressor may be available from a parts-store loaner program.
If it's an intake gasket, it could be a simple fix. Replace the intake gasket. Change oil 'n' filter, pull the plugs, crank engine to blow out any remaining coolant in the cylinders. Put it all back together and drive away. Change oil 'n' filter again in a few hundred miles to assure that all the coolant is removed. Hope that the catalyst isn't poisoned. Depending on the results of the cranking compression/leakdown test, and the cooling system pressure test, this could be very do-able.
If this is your truck, why is Dad telling you what you can/can't do?