When you get a chance get any spray bottle or a hose and mist the engine while running at night in a dark area. If you have any wires or coils etc that are arcing, you'll see it easily.
What is a boost vacuum leak? If you are in boost, you would be pushing air out not pulling a vacuum.
Keep yer $20, here's the solution. The problem is between the seat and steering wheel. You are welcome. (ps..that time I insulted you, unlike the last time I posted to help you out and you went all libby on me)