1999 GMC Sierra Z71 throttle stutter

1999 GMC, 5.3L V8, auto, 160000km. Recently the truck would stutter when accelerating, almost every time when first started and 50-% of the time leaving a stop like a red light. Basically push the pedal but no response from the motor. No miss or back fire, felt like lack of fuel. Fuel pressure is good, filter is new too. Throttle position sensor was weak and changed, and I als cleaned the throttle body. It was very dirty. Response has been better, and mileage picked up about 2 MPG. Truck still does act sligh stutter, most notable when first start the truck and drive away, for the first minute then all is ok. Does not do it every time, nor to any pattern. No codes up on the motor.