1998 f150 4.2l. New water pump, thermostat, upper and lower intake manifold gaskets. Heater hoses will not circulate hot coolant. Heater core flushes clean with no resistance. Radiator flushes clean with no resistance. Upper and lower hoses heat up as normal. About to put a bullet betwixed the running lights. What am I missing gang?

 

There is only one or two things...

1. Air pocket.
2. Bad thermostat.

I'd do the easy thing first and check that thermostat, put it in a pot of boiling water and see if it does anything.

 

I can hear it pop open and then the upper radiator hose gets hot. Think the thermostat is ok. It is also new.