My 99' does this since I got it, if it's idling at 700-750RPM warmed up and I quick blip the throttle 1/2-WOT in neutral or Drive, especially noticeable if I actuate the throttle from under the hood(a quick miss than throttle up), the only thing I haven't checked is valve clearance, front O2(FED) or another ECU which isn't easy to do on an immobilizer system. Done OEM MAF, TPS, Wires, Plugs, cleaned IAC & TB, compression test 195, fuel trims are normal now, new ATF and OE filter, checked timing marks, checked Crank rotor and crank pulley bolt, ran a ton of premium and Lucas fuel conditioner cleaner, Scoped cylinders-carbon minimal?, I have to induce it with an abrupt throttle blip ON/OFF. My 97 with double the miles and only used as a plow truck, doesn't do this but it has a different MAF and injectors, I began to wonder if this is a 99+ Thing it doesn't effect the way it drives just a weird hesitation/throttle cut if your goofing around, I'm considering swapping TB's incase that throttle stepper just isn't set up right.