Go get a thermostat, and pay attention to the stem length as you've changed your water pump and there are two versions. I believe your 1995 should have come from the factory with the short length as they changed to a longer version in 1996, but either water pump can be installed. Come to think about it: that really might be part of your problem. Unfortunately, you can't really trust taking your old one out and matching the length because you changed the water pump, and could have put the newer version which takes the longer stem length thermostat. Lots of history on updates, 195 versus 205 degree, short versus long stems, etc
Google is your friend, do some reading, but at this point I would highly suspect you have a bad thermostat. If it was me I'd do everything to verify the correct stem length and put a Motorcraft only part in it.