I have a '89 Chrysler Lebaron T1 with cooling issues. The temperature gauge when driving swings from 1st mark above cool to 3/4 hot and then swings back down to cool repeatedly (car does not overheat). I've changed the thermostat ( with drilled hole ) and made sure all air was purged. When I got home from a twenty mile ride I could open radiator cap and no explosion of radiator fluid when I opened cap, in fact the radiator cap was cool. Both upper radiator & lower hoses feel hot. Radiator fluid has been changed every one to two years. Water pump is three years old and has only 15K miles on it. Any ideas ??