I converted a few years ago and now sometimes I’m the sheliach tzibbur during pesukei d’zimrah on Shabbat Kodesh. I was advised to say "shelo asani goy" because everybody says it this way and this is the original text of the Morning Brachot. But now I read in the Mishnah Berurah that I should not say it, because first I was a goy... (that’s true). What should I do?

Although the Shulchan Aruch says that a convert should not recite this bracha, many poskim disagree. Therefor, in the case in which a convert is "sha"tz" he should say the bracha. It is not necesarry to avoid being a shaliach tzibbur because of this.