Why does my vehicle hesitate when I hit a bump at 55+ mph and its warm outside? on 2001 Jeep Grand Cherokee

My 2001 Jeep Grand Cherokee runs great. But when the outside temp is 65-70 degrees and driving at 55mph or greater and hit a small bump like a seem in the pavement or a pothole, etc... it will hesitate sputter for a few seconds. I have tried a tune-up, shocks, sway bar, steering damper, ABS, brake pads, brake calipers, throttle sensor. No luck so far.

Asked by for the 2001 Jeep Grand Cherokee