Not sure what the AC/D tap is?
Vacuum should drop when throttle plate opens, engine vacuum is highest at idle then gets less and less as RPM goes up..
RPM should increase with small vacuum leak, i.e. sucking air, that is normal, that's how the IAC controls idle RPM(IAC = controlled vacuum leak), but it should stumble a bit when throttle is opened because of the unmetered air coming in from the open line.
38deg "B"TDC?
Find that Spout and unhook it for the timing test
You want 10-12 BTDC