surging idle when in gear and stopped

[zachary A makoff]

I have a 98 k1500 with a 5.7 in it and I am having an issue once the engine has warmed up at bit an when im at a stop light not moving the engine rpms start surging. It only does it in gear, when I put it into park it goes away. Any Ideas.I replaced the distrbutor with a summit racing aluminum one, put an Accel igition coil, acdelco ICM, IAC is a year old as well as the mass airflow and knock sensor. acdelco intake temp sensor.