I have researched high and low, and I believe I have tried everything, but wanted some more other opinions. I have a high mileage, 354xxx, 6.0 that has the shudder between 45-60, or whenever just cruising in overdrive. Anytime in overdrive and I try to lightly accelerate it shudders, and sometimes bucks, but wont downshift unless I really get on it, and then it feels fine. I have just recently done a ton of work including new oil cooler, ficm wiring harness, icp sensor, ebp sensor, hpop gasket, and egr delete. After the two sensors it seemed better for a few drives and then eventually came back. Just before all the work I did an oil change with syn T6, and have also added archoil with no change. I have a scanguage ii, and icp pressure is good, as is ficm voltage, and my deltas are right where they should be. Any ideas what else it could be? I have read that it could be injectors, but it does it cold, and hot, and the archoil seems like it should have done something? Any help would be great!!!