Same thing happens w me around new people. I also am more fluent when I’m angry-stressed, and with emotionally charged conversations (small talk can be very difficult). Try telling those new people that you are a PWS - adding that you are mostly telling them for your own benefit, and you aren’t looking for them to do/say anything about it. Awwwwlso try intentionally, slowly, extending beginning of words/sentences - while keeping eye contact. And continue talking sloooowly with more enunciation of all sounds. Those “techniques” give your brain the message “It is ok for me to take up space in this conversation”