Just suggestions May not be the problem, I always start with the basics with turbo cars before I make it a month long project for a set of plugs or something simple

fyi, my old turbo escort would blow out the plugs at the heaviest load i.e. 3000-4000 when the little ihi turbo was spinning the fastest, any time after that the ihi ran outta gas so to speak and it didn't feel like it was breaking up any more, I changed out the plugs and didn't have that problem again.

I got a little excited with the boost and blew a rod out the block a few months later though .