I used metallic thread for some straight line as wel as FMQ this winter. You are having the same sort of problems I had, til I found out the "how to's" from my dealer.
There are a lot of variables in metallic threads, so there is no one set answer. Also, different machines will require different actions.
Definitely use a metallic needle.
For my machine, there were instructions in the manual, which did not make sense, but once I spoke with my dealer, it did!! There is a lubricant well to feed the thread thru. Plus the spool of thread needed to be fed out of it and into the machine in a different way than I do for conventional thread.
Once I had all that set right ... there was no need to adjust the tension and it stitched perfectly!
Another time, if I have a different metallic thread, it might be all different!
For sure, I will buy my thread at my dealer, and check with them as to the how to.