Glad I could help, i would still recommend seeking more professional advice before going into the engine because I am still quite the amateur
but the test is easy to do.
While you were doing the regular tune up did you adjust the valves? This is likely not the problem, but I just had my valves adjusted and it fixed my idling issue and the car drives a lot better, I also had 30k miles. Its also good to get the basics out of the way.
Keep us posted on the throttle adjustment