99 LHS surging and stalling
 

Hey everyoe Im new to the foroum but a pretty advaned tech I am dealing with an issue that has me stumped 99 lhs no codes runs fine till it reaches operatimg temp then it starts to surge and sometimes stalling out happens worse when in gear or if ac is turned on drives fine till u come to stop i replaced the IAC but made no diff any help or suggestions would be awsome