An implantable medical device is provided that comprises a pulse generator circuit that times delivery of ventricular pacing pulses based on a base intracardiac interval (ICI). A processor is provided that has memory storing program instructions and storing atrial and ventricular events over multiple cardiac cycles and that is responsive to execution of the program instructions. The processor adjusts the base ICI by an ICI adjustment, during one or more of the multiple cardiac cycles, to promote intrinsic heart activity. The processor further counts a number of the cardiac cycles in which the ICI adjustments occurred in conjunction with arrhythmias to identify an excessive adjustment count and modifies the ICI adjustment to utilize a new ICI adjustment based on the excessive adjustment count.