2001 Chevy Impala engine running hotter than normal

Engine Cooling problem
2001 Chevy Impala 6 cyl Front Wheel Drive Automatic 91kmi miles

the low water sensor was replaced and the engine was ran before cooling sys. Was bleed and bleed screws where opened while running now it gets hot enough to have the fans come on cools a little the heats back up the thermostat was replaced but did not help also the temp seems to go up is spurts jumps a mark at a time then stays there for a while then goes upm again