1988 k2500 with a brand new gm goodwrench tbi 350 and 700r4. On the highway with cruise control on at 65 when it hits a small hill and downshifts from 4th to 3rd the cel will come on with a code 43 (knock sensor). I can get knock counts on tunerpro when i hit the exhaust manifold with a hammer. When im out driving i dont see any knock counts. Not even when starting it up. Also the connection i have between the ecm and tunerpro is pretty crappy. When you are sitting at a red light just idling in gear it shows connection error but the second you hit the accelerator to take off the connection restores. Anyway i need help on what to try next to get rid of this cel from turning on.