2002 Ford Explorer xlt 4.0 keeps running hot.

My 02 explorer keeps running hot and needs some
advice.  I have replaced the water pump cause of
weep hole was leaking out of pump. Also, I have
replaced thermostat and used temp head gasket fix
and got the white smoke to stop coming out of
exhaust.  There was no coolant in oil and I've done
oil change and flushed radiator 5x to make sure the
coolant would be clean. The heat in cab isn't very
hot unless driving down road. So I went ahead and
bypassed the heater core of that was the problem
but no fix. It seems when the truck is running on
operating temperature white smoke comes out of
reservoir and seems like there is a lot of back
pressure on thermostat hose and whistling sound
coming from somewhere. Do you think this is a
head gasket issue still?  I think it could broke on the
exhaust side of head gasket