goes from 600 to 850 roughly. could this be mass air related. a couple of weeks ago the tube after the mass air disconnected and i ran it like that for a little bit. it didnt disconnect all at once it just kinda gradually slid off. the car started to ping and i played with the timing for a couple of days till the whole tube slid off and showed me what the problem is.. it started to slide off the bottom first, thats why i didnt catch it. i also had a plug wire get a little to close to a header at the same time. that combo = really bad running car.