bogs down and bucks bad at high rpm's.
03 ranger edge, 2wd, auto, 3.0; 6cyl. 54,000 miles. When driving, usually up grade and try to accelerate, truck bucks real bad and bogs down. already changed fuel filter and plugs. (also did oil/filter change and x-mission service). No engine codes. At normal speed runs great. Drive 75 miles one way every day, last 40 on I-75 south into Knoxville, several big hills, kinda scary not being able to accelerate around big trucks on some of those grades. any idea's?