506 fault code when AC is on

getting a 506 fault code ( idle too low ), when running my AC, someone suggested replace the IAT. If I run without the AC on the code does not come up. it seems when i''m on the highway everything is fine , when i''m in heavy traffic the air gets warmer, i can feel the engine stutter, the code comes up and it begins to blow warm air. when i''m back on the highway the cold air returns. any similiar problems out there. only happens when temperature index gets near 100.AC system is fully charged, oil changed every 3K 109K on engine



''03 Accord EX 4dr 3.0L V6 auto