water temp does not stay up after thermosta opens up first time
start truck - warms up to 190 stat open gauge drops and goes back up to about 165 to 170 then swings back down this keeps on repeating. radiator has been changed stat has been changed. Gas consumption has been bad, I know water temp has to be up and stay for normal running. got for sale sign in front of rad to help hold temp up. any help would good.