I've got a 2003 Trailblazer.  It was running fine, then out of the blue, I tried riding it and it would start and idle fine, but when I get on it, put it in gear, and hit the gas, it bogs down and stalls.  If I "suffocate" it, or restrict the amount of air going to the filter, it will drive w/o stalling.  As soon as I take my hand off the air intake and allow the standard amount of air through the filter, it bogs down and stalls again.  I've tweaked the carb. idle screw with no luck.  Any ideas?  Spark plug bad?  Air filter & foam sleeve need replacement?

I did have a mouse in the belt drive area, but I cleaned it all out.  Still won't drive.  Please help, I'm going nuts!  

sounds like the fuel mixture is too lean.

check to see if there is water or trash in the fuel tank and carburetor.  

I changed the gas in the tank and replaced the fuel filter.  Still didn't work.  

try adjusting the fuel/air mixture via the screw on the carb