My 98 blazer will not start has no spark on 1998 Chevrolet Blazer

Was running rough engine jumping around wen running little exceleration power, replaced plugs wires cap rotor, and coil, had module tested said it was still good. Was having misfire on 2 and 4 so did tune up, it helped a bit but seemed out of timing, went to start it and it backfired and won't start now so pulled the coil replaced it and tested the module but even w a new coil won't start, its trying but still not getting spark, its getting fuel. I'm at a total loss, could the timing be way off???

Asked by for the 1998 Chevrolet Blazer
If you are sure it has NO SPARK replace the distributor assembly!