2000 Chevy Impala Can you please help

2000 Chevy Impala 6 cyl 160000 miles

I have a 2000 chevy impala and I have a ton of problems. My car drives great when its cold but when it warms up it drives terrible. When I get to 40 mph my car shakes until I get past 50 mph then its fine. Second when im going up hills my car jerks, I have to step on the gas to get more power so it doesnt hesitate. Third. After my car is warm, when I come to a stop sign and press the gas before it switches to second gear it jerks about 3-4 jerks really quick then its fine or when I turn in first gear it hesitates for 2 seconds then its fine and last my car seems like it gets hot. When idling it goes past the middle marker on temp gage about 2 notches then goes back down but when im driving it doesnt get hot. Any ideas? I just paid a mechanic to fix my gaskets in my motor because it use to leak water, they did a fuel pump, fuel filter, ignition switch, etc.