So I have a 92 2.8 s10 and it's been missing fire. I unplugged the tan wire under the dash and timed it to 10 degrees with a timing light but it's still missing and it backfires during deceleration if I don't push in the clutch. I did the jump wire scan and it's showing code 13, code 34, and code 42. I'm assuming code 42(est) is the problem but could the map sensor (code34) of the o2 sensor (code13) cause the est to malfunction? Is there anything I should do before replacing parts? I recently changed plugs,wires,and the rotor... could the distributor cap cause this problem?