How do I learn to talk?

I feel like I suck at making small talk and I really struggle to hold a conversation sometimes and then I feel like I just make things awkward. This was made so apparent to me when I had an interview today.

When they were asking me technical questions things went great I was holding a conversation pretty good and it just went smoothly. And then when the interviewer switched to like behavioral or situational basic question I was like deer in the headlights. The questions were so basic like “Reflect on the time you had a difficult coworker and how you handled the situation” dude I was mumbling my fucking ass off and I cringe anytime I look back at the stupid shit I was blurting. And it made me realize that I’m just not that good at talking. I am a good listener however I’m jealous of people who can just yap nonstop.

So how do I get more adept at talking? besides talking to more people that advice doesn’t help me at all, what techniques build this crucial skill?

I’m not like an introvert nor do I think it is a confidence problem, but I get easily flustered when someone asks me something and I immediately don’t know the answer at that exact nanosecond, and it ends up with me saying some absolute buffoonery that will make me want to shoot myself in the head with a shotgun.

The only times I can have a successful yap session is either when I am enthusiastic/knowledgeable on topic at hand, or when I am under the influence of alcohol or weed.

Anyways I need tips badly.