I put long tube headers on and had an issue with my O2 not going into closed loop at idle and cruise today I installed a heated O2 and that fixed my open loop issue but the sensor will fluctuate voltage from 0 to 900 or so in datamaster. If driving and I let off the gas to coast the sensor will read 0 for a bit. Is this normal? I never really paid attention to this in the past. 7730 Ecm 8D

 

Sounds pretty normal to me. The fluctuations are the ECM "chasing" the O2 sensor attempting to maintain the correct AF mixture. Letting off the gas will cause a momentary lean spike too.