I only used one autoXray to scan my 1995 GMC Sierra. 350TBI. The O2 sensor readings went up and down, which I understand is normal. My question is, it is normal to go from 100mV 850mv up and down again and again. Are these numbers within a acceptaboe area and is “consistent” normal fluctuation. All other sensor readings appear normal and the truck is not sending any codes. I just stutter the hunt for a miss / for a while now. Connector, cable, cap, rotor and ignition coil have been been changed as part of a tuneup in the week. The throttlebody been cleaned. Please help.