when i take off at wot and let off quickly like in (1/2 block) the auto tranny stays in that gear either 1 or 2 for about40 to 50 yards, this is after i now mash the throttle half way down or more it feels like it is stuck in that gear, it doesn't want to shift, then in 20 seconds or so, every thing goes back to shifting like it should. Normal or not normal?