Slver87si

Anyone ever had to bleed their coolant system? For the longest time I thought I needed a new throttle body or tps. I ended to taking my car to a place that specializes in classic cars that has a reputation for wiring and pre obd2 troubleshooting. They showed my a bleeder port behind the distributor. Had to jack my car up to make sure it was the high point in the coolant system and let the car warm up a bit before cracking it to let air out. Turns out my car had a pinhole leak in the heater core and that let air into the system until one day it was enough to cause the engine to surge at idle. any idea why a bubble in the coolant system makes a Honda engine surge?