Shouldn't be a boost limit because it's has a stage 3 chip and it's ran fine just lately.

CosRush, that's exactly what mine is doing. I booted her in 2nd and it was coughing and spitting before I backed off, but in 3rd where she is under more load it was just one big bang then I backed off immediately. I'm gonna go out there in a mo and have a look. She seems to be running fine, it's only happening when I floor it and it hits big boost at around 4000rpm.