strange resistance readings

I have a 95 blazer, 4.3, auto, 4wd. runs fine up to half throttle, then hesitates and bogs down. I replaced to throttle position sensor and noticed something stange--when I measure the resistance directly at the sensor, it ranges from 1.8 at idle up 6.8 at wot, I believe that is an acceptable range. However, when measured through the pigtail, idle is roughly the same, but it tops out around 2.5 (coincidentally at about half throttle). Is this right?, if not how do I go about fixing this problem? Thanks-- Nick F.Y.I.-Nearly all ignition components are new as well as the fuel pump and filter.