If the ICP is new....ish then it sounds like your IPR is STICKING SHUT and HPO pressure is building just briefly enough to send more fuel than desired. Either raising HPO pressure or increasing Pulse width on the injectors briefly will cause it to raise RPM. Are you having any transmission issues? If you have an automatic and the flexplate is cracked.........that is a large stretch so I am going with IPR.
Dwayne