i have a 1998 dodge ram 1500 5.2L i've replayed the t-stat, rad, heater core on 1998 Dodge Ram 1500

and the water pump and the upper hose is hot and the lower hose is cold. it sounds like a flow problem but can not find or know where to start. still has heat but temp gauge not reading right.

Asked by for the 1998 Dodge Ram 1500
Take out your t-stat to verify that you don't have plugged up water jackets in your engine. The coolant should really flow. I have also seen an after market t-stat not flow properly, so be sure of that. If the coolant flows and both hoses get warm-hot, then you may have gotten a defective thermostat.
1 more answer
Your heater core is plugged.
Reverse flush it with water and air.
I have done mine a few times now.
I get pieces of gasket looking material out every time.
Works great for about a year and then I do it all over again.