Large RPM and Vacuum drop when shifting from park to gear
I don't own a timing light,
To cure this problem, that's actually a good thing. just follow my previous post, #11. No timing light needed.
The only thing you need a timing light for, is to set the Power-Timing to an amount less than what will cause detonation at WOT. But since you are just guessing, and then road-testing to listen for it, or to feel the power loss, or to witness the loss of speed on a timed run..... and then making an appropriate change, you can even get away without a timing light for this.
Having a lite just makes dialing it in a wee bit faster. And perhaps a tad safer.
As for setting the idle timing, to an arbitrarily chosen number;
if your engine wants between 10 and 19, by single degrees, there is a 90% chance you will chose a wrong number.
If your engine wants between 12 and 16, there is an 80% chance you will choose wrong. But, by single degrees,if you guess wrong every time;
there are actually 5 choices the first time, 4 the second, 3 the third, 2 the fourth and finally the right one comes up. So that doesn't total just 5, it sums to 15. At least that is what they taught us in math class. Question everything!
The method in post 11, will get it right, the first or second time, because the engine will tell you what she wants.