I forgot to add this to the previous post.

while changing my water pump, thermostat, and hoses today I came across a first in all of the years I have been working on cars. The thermostat was nearly in pieces when I took off the cover to replace it. The small band of metal that holds the spring compressed was torn off on one side. I suspect this is the cause of intermittent elevations on the temperature gauge. After changing the pump today I drove the car about 40-50 miles in 90 degree heat and the guage never went passed the lower half mark of the gauge. I have never seen a thermostat damaged upon replacement.

thanks for all of your suggestions. the oring on the pipe trick solved my problems.