95 Astro engine temp reads low

Hi, my 95 Astro temp gauge reads about 160 under most operating conditions. I just pulled the thermostat and boiled it in water, opening at the correct 195 degrees. To check to make sure the temp sensor was working I drained some coolant and ran it until the gauge went all the way to the red zone. Still may be the sensor, don't have a ohm/temp chart to check it. Before I buy a new one could it be something else-gauge/wiring? The sensor only has one wire, was it later they went to the 5v reference sensor? Is the low gauge reading making it run rich? Thanks!

To check to make sure the temp sensor was working I drained some coolant and ran it until the gauge went all the way to the red zone.
Ouch, that was kinda severe since a sender is under $10. replace the thermostat, temp sender and radiator cap all at once, probably around $25 total,and at that age they all need replacing any way, and see what happens. my bet is the rad cap isn't holding pressure anymore.

Your 95 Astro has 2 temp sensors: one for the computer, (intake manifold near the thermostat) and one for the gauge, (left cylinder head between plugs 3 & 5). I believe 98 was the first year that only one sensor was used for both PCM and gauge. Class 2 communications are used to send data to the temp gauge in the dash. If the engine is in fact running cold, the PCM will richen the fuel mixture and cause a drop in fuel mileage. Eric's suggestion will most likely take care of the problem.