hello i have a 97 blazer 2wd gets code po 300 flashing cel also no spark on #1&#2 plus foul odor like clogged cat new plugs and wires also replaced cat 4 to 6 weeks ago thanks for any help

 

Have you read through:
P030x Explained (x=0,1,2,3,4,5,6)
and
The dreaded P0300 CAUTION LONG POST