I have a 96 blazer 4x4 and sometimes it doesn't want to start and just turns over and when it does it idles at about 200 rpms and will die if you don't give it any gas but if you touch the pedal it goes to normal rpm and idles fine. I am not getting any codes from this. Any help is appreciated. Thank you

 

Got to be a code hiding in there some where. That condition could throw any number of codes.

 

I went and checked again and there was an evap malfunction and catalyst below threshold, so would it be the evap doing it ?

 

Yes it could, so could the catalyst issue. need to start looking for vacuum leaks also.

 

What is the catalyst ?

 

Catalytic converter. You probably are showing a bad O2 sensor , that or the cat is bad.