Some time ago i had a rather frightening experience with a dose of 300 mg syrian rue extracted harmalas and 200 mg of oraly taken spice , which i thought would being a medium dose at that time.
I however turnt out to be something that i do not really want to repeat.
It basically involved a trip that went from being very good and promising, i even remember thinking something like , that is really nice i could have taken more next time i can increase the dose to get a deeper experience to absoulutly undescribable and unbearable intense. Before i got that intense i actually thought that after about estimated 3 hours in the trip i had the worst behind me. I started to get for unkonwn reasons very
strong nausea, the worst i ever had actually, and just at the same time, were i was in the most pain (from vomiting) the trip reached its peak, than a new peak after that always as i thought it could not get any worse. It really was that bad. There was so much about it that was terrifying that i dont think that my englisch is good enough to describe it in detail, not that it is possible anyway.
However it was very frightening and a estimated double as long experience as i expected it to be, which i think was caused from the high dose of oral taken harmalas.
Since i absolutely do not want to experience that again, at least not for felt hours, i want to make sure to take not to much harmalas again.

Because of that i have some questions, i hope someone can help me with them.

Is it possible, if a mao inhibitor is taken orally lets say 200mg harmalas and than spice is vaped, that i find myself in an hour long trip?
Can vaped spice accumulate if a oral mao inhibitor is taken beforehand
For example if i vape 20mg than 30mg spice after having taken oral harmalas, can i accidental get similar effects like i would from 50mg of spice taken at once?
Is there a big difference between a oral partial mao inhibition and full mao inhibition, which i probably had in my last pharmahuasca journey, because i think 300mg harmalas should have given me that.
How long would the trip duration be with this combination oral mao inhibitor and vaped spice?

I've had experiences exactly as you describe.
A few things were at work to cause that.
You probably ingested too much harmaline for your body chemistry. I find more than just a little harmaline too heavy and 250 mg or more of harmaline/harmine mix can be debilitating whereas I can take 500 mg of pure harmine without any problems. If you look at the VDS protocol for harmaline/harmine separation you can see how to reduce harmaline. Even if you don't have the equipment to do the separation 'correctly' you can still use ammonia and vinegar to split harmaline/harmine mix into a much richer harmine/harmaline mix plus some isolated harmaline. That is something to consider if you find rue harmalas too intoxicating and debilitating.
The abrupt and shocking second peak you got is thought to be due to the liver or gall bladder retaining much of the DMT until it is released all at once. This, apparently, only happens with oral DMT.
I don't currently have nearly as much experience with oral harmalas alone + smoked DMT as many others here, so give the advice of others more weight, but in my experiences to date I took oral harmine an hour before I started smoking DMT and THH hydrochlorides two hours before [oral harmine takes 90 minutes to get to its peak, THH takes 2.5 hours, harmaline takes 60 minutes] and each smoked DMT dose came on fairly fast and lasted 25-30 minutes before I was ready to either dose again or rest and relax. The one time I added freebase harmine+THH on top of the DMT didnt seem to change that timeframe. I'd actually like for it to last longer. I have more experimentation to do