1996 12V with 116,000 on it. THermostat has been stuck open for quite a while ( Temp gauge has not got off the Cold in a while, used to run middle of the range). Driving today and temp gauge reading "Normal" right up the middle. Popped the hood and Pressure cap was COLD. Let it sit few minutes and when I came back ( About 20 min after shut down) cap was HOT as it should be. Water pump was just replaced about 500 miles ago. Is there a bubble in there? Thanks!

 

Highly possible......did you loosen the plug above the thermostae and try to blee air out? It takes a 3/8 or half inch drive ratchet, can't remember.