I do not have access to a Quarterhorse, but I like the idle lope.Of that I have no doubt. People just start ripping mess out and cause tons of problems.
The EGR and air injection system are the source of lots of issues with these cars. The EGR valve has a tendency to get stuck semi open due to carbon, causing codes and the car to run like crap. The diaphragm cracks and causes vacuum leaks. The bundle of vacuum lines for the TAB/TAD solenoids have a tendency to break and leak causing more vacuum leaks and running like crap. The air pump has a tendency to lock up.
I my opinion it’s nothing but a headache. Mine is completely removed with the vapor tank and purge valve being the only thing left. I did it right by property removing everything. I now only have a couple of vacuum lines and my passenger strut tower is super clean.
I do however have a Quarterhorse with a custom tune that has the EGR and thermactor systems disabled.
If you’re going to fix it you have to do it like you did and fix it right. Working correctly it’s not a problem and really doesn’t rob any horsepower.
I have not had problems with this air pump. But my 79 flung the Air pump pulley across the parking lot and it rolled onto the fairway when it was parked. No unusual noise when I drove it there, but everything came off the shaft.