Trailblazer Carb Issues

[josh200396]

I have a 99 Trailblazer 250. I'm having issues with the carb blowing fuel back into the air box. I have pulled the carb off and ensured all orifices are clean and reinstalled and I'm still getting the same problem. It seems the motor is blowing back just as hard as it is sucking. Its soaking the air filter and puddling between the air box and carb. I have adjusted the idle mixture screw all the way in and backed it out 1.5 turns as suggested in the carb sticky. I've also tried it in every conceivable position possible. So...
Should the motor be blowing back through the carb?

I would assume that if the motor should have some blow back then maybe my carb is still messed up and flooding the motor with excess fuel which is getting pushed back out by the blow back.

[josh200396]

Just to update my troubleshooting. My brother has an identical trailblazer. I just took his air filter out to see if he has blow back. His has none. So what is causing my blow back problem?