About 4 weeks after I started vaping I reached a point where none of my kit seemed to work for me - no taste, no draw, burnt tastes, horrible tastes etc and I felt as though I was on the verge of going back to the fags. I spent quite a bit of cash but now have a choice of kit that I know will give me a solid vape and I usually have 4 or 5 on the go at the same time to avoid chain vaping. I also managed to get through March only spending £20 so I feel like I'm reaping the reward now.
So, I did the following, hope it will give you some ideas. I'm MTL and don't need a throat hit.
I read through a thread about the Artery Pal II Pro/Artery HP Coils and there was a lot of good feedback about it and it's not too expensive. I decided to give it a go, using the 1.0 coils. I'm now almost exclusively vaping Dinner Lady in this because I like their flavours, they're consistent and they give good flavour in this set up. I also dropped my nicotine level from 18 to 12 and find that is a more satisfying taste. I tried nic salts but they make me cough so just do normal freebase now. I now have 2 of the Pal II and I take a couple of draws from one and then a couple from the other so I'm not chain vaping from them. I also bought several spare 3ml tanks for them so I can swap around with flavours at different times of the day.
I always start at 9 watts and usually end up about 10 or 11 never much higher.
I also read through the thread about the ThinkVape Zeta. It's a bit heavy for me and I don't like the separate battery but I have to say that with the 1.0 coil again I get a great flavour. I don't take this out and about with me - I'm actually a bit scared of the big hefty battery :-)
I also have an Innokin Adept zlide that was awful with anything I tried and was the worst for the burnt, horrible tasting coils. I had a pack of 5 coils, 3 of which were useless. It almost got chucked but I read a post about using 1.6 coil with Manabush liquid. At about the same time, Manabush launched their Tribute range and it's almost like they were made for each other. I use this for my late afternoon/evening vaping because it's for long, slow, relaxed vaping, savouring the flavours.
And I have experimented with drip tips. I prefer the long narrow tips and I have quite a few so I can put clean ones on frequently to refresh the taste and particularly now with the coronavirus. I do think that drip tips play an important part in the vape experience - different types give a different draw and if I don't get a good draw I start hammering it and that's when I get the coils playing up.
I prime my coils the same way you do except I usually leave them longer before using them, sometimes I even leave overnight and find it's better in the morning.
And the last thing I found was that I was really pulling on the draw the same way I would drag on a fag. Now I'm much more refined and let the kit do the work rather than panic about getting a big hit out of every draw. If I start to get a funny taste, I realise it's usually because I've been pulling rather than vaping.
Sorry for the long post but I hope it gives you some ideas.