Little Red Stang

I have a 96 3.8ltr. Mustang. Recently I have had a problem with my coolant going into the reservoir and not back into the radiator. Change Thermostat, radiator cap, and flushed the system. Now my temp gauge is running higher than normal. (right in the middle) I have almost 300,000 miles and replace drivers side head gasket about 6 months ago. Does anyone have a suggestion and please don't tell me I have a head gasket leaking, because that is what I fear the problem is.