I have a 2000 s10 4wd, when acceling the vehicle will stay in that gear till you let off the gas then it will switch, i have watched it through transmission data, also when the vehicle warms up you can put it in park and put the rpms over 2000 and the spedo will fluctuate between 0-3 mph. anyways have any clues?

revised notes: 4.3L, I noticed bulletins on over oiled after market filter, this vehicle has one, but I checked the maf sensor and it is ok, reading normal, even with a new one acts the same, throttle pos sensor reading are correct as well, wiring harness is without damage and pins are ok. vehicle also experience lunging during acceleration.