sheajk

looking for answers.. i have a 1987 350 tbi. the issue is backfiring through the intake when quickly accelerating, and lack of power. codes never come up usually but once i got code 43. the code reader i have shows a knock signal of 17 that i cant get rid of. i unplugged the new sensor i put in and the signal stays at 17, shouldnt it go to 0? also when i unplug the ESC the knock signal goes wacko, with every refresh of the reader i see anywhere from 300 to 4 counts!! what in the crap id the deal? when i ran through the troubleshooting logic chart for code 43 i ended up at the CKT 485 open, shorted to ground or bad ECM, ran a new wire to ECM and replaced ecm but same issue. according to the chart my ESC shouldnt have an issue but im not so sure that it is not the culprit.