I looked through all the topics and couldnt really help me. so my problem is i did a swap with my friend on his 91 ac. put in a 97 ls motor. car runs fine and all but when hes stoped the heat works fine when he starts to drive the temp goes down and the heat gets colder. temp gauge doesnt even hit 190 deg and if he starts beating on it the heat goes low and so does the temp gauge.