2000 5.3L 2wd, runs ok part throttle but seems to just make a lot of noise past that--revs come up as they should, but doesn't feel like it's making the power it should. No service soon light, no indications of anything wrong that I can see. Partially plugged converter has crossed my mind, maybe related to my trans problem as posted a bit earlier? Highway mileage seems ok, 20 or so on the last trip I checked it on, doesn't seem to be suffering in town either. Any ideas on simple things to check?