in the past ive had some overheating problems, i replaced the tstat with a 180* one, got myself a 3 core radiator, and thought the problem would be solved. i dont have a blown head gasket. it runs perfectly while im driving in my higher gears like on a freeway but when i hit the low gears in the streets the temp creeps up. what could this be? 
please help me out. i let the car idle on saturday for a good 40+ mins and it never overheated, i took it for a spin around the block and it seemed ok. today i drove it across town what should be 30 min drive, and this is when my problems surfaced with the creeping temp. as soon as the temp was rising i pulled over to take a look and i hadnt fully tightened the upper rad. hose 
was this my problem?
please help me out. i let the car idle on saturday for a good 40+ mins and it never overheated, i took it for a spin around the block and it seemed ok. today i drove it across town what should be 30 min drive, and this is when my problems surfaced with the creeping temp. as soon as the temp was rising i pulled over to take a look and i hadnt fully tightened the upper rad. hose was this my problem?
