BCDD Vacuum Line

Well the replacement master vac fixed the brake and idling issues, as expected. But after driving it for 25 miles or so, the sticking idle came back. I pulled the throttle body off again and cleaned it but to no improvement. So I took a deeper dive into trying to recreate the issue… turns out, when the car is off, the throttle has no problem returning to the closed position but when the car is on, it stays open after lightly applying throttle. I’m guessing the vacuum in the motor is providing enough resistance to hold the thottle blade open slightly. The sudden blip in the throttle forces it closed just due to the momentum. I sprayed some wd40 on the throttle body shaft/springs and it seems to be working better now. Nevertheless, seems like a short term solution… has anyone replaced the return spring to something more “heavy”? I took the spring off and it seems very easy to stretch it, might help to have a heavier spring rate on it to overcome the vacuum, if that’s the issue… any ideas for a longer term solution, apart from going to a cable setup?

I have a third spare throttle body that I could completely disassemble, lubricate, etc…. Anyone have a diy for this? Including replacement components?

Edited September 8Sep 8 by dar5052