05 grand cherokee 3.7 , running hotter than usual

3.7 engine my laredo 05 is running hotter than usual, got a check engine for o2 sensors and misfire code, swapped out the dead o2 sensor, now i have a misfire code, it runs smooth , i did a sea foam flush using 2 bottles ,i ran 1 bottle through the brake booster line,and half in the oil and other half in the gas tank, i let it all sit for 30 mins then drove for 50 miles and changed the oil to full synthetic, still throws misfire code po300, changed the spark plugs to copper and gapped them,the temp cage never passes the middle line, about a week a go i noticed the car running hotter than normal, thats why it burnt out the 02 sensor, all fluids look good, after reseting the battery and changing spark plugs ,check engine light went away , but i know that the car is running hotter than normal, and its throwing the system off, how do i fix this issue , mostly drive in city car runs all day long , also i notice lets say I'm driving and pull up at a red light and and my foot on the brake, i notice the mpg start dropping and its starts running hotter than normal but with out overheating,

thank you