So I just signed up for this site after researching it for the last couple years. I have a 91 k2500 bone stock tbi other than ultimate tbi bench top mod, 3” free flow cat and muffler. The problem is hesitation under light load with throttle held in same spot then it catches up and takes off again, and so on. No codes and I have literally replaced every sensor and and engine Managmemt items with “nos” parts. Brand new “nos” ignition with pertronix flame thrower coil and D.U.I plug wires with stock delco plugs. I have 160 psi in all cylinders 20 hg vacum at idle fuel pressure solid at 14psi and does not change when hesitation occurs. Brand new rebuilt 700r4 with corvette servos and beefed up a little. I just bought another truck with the exact same motor that runs excellent so I had somthing to compare with.swapped tbi from that truck to mine, still same hesitation issue. I have looked and searched and searched again to figure this one out. Bought the factory service manual for it as well. I am not very computer literate and that is why I haven’t done any data logging with tuner pro or win aldl, I do have the brick though to make sure sensors are within spec. I look forward to any help and direction, i am BEYOND frustrated.