2003 Ford Taurus Barely runs above idle

Car driven regularly - ran great. Replaced original water pump as preventative maintenance. Disconnected battery and CPS connector. Also greased squeaky cam position sensor drive. Changed oil. Started to check repairs, seemed to run fine. Pulled outside and left for a couple hours. Got in to drive an had noticeable lack of power. Further driving in subdivision resulted in more degradation. WOT would get maybe 5 mph w/surging. Finally, held WOT, RPMS would start at about 1500, and decrease till engine died. Restarts immediately and idles fine, just wont go above 1500 rpms and then dies. No CEL and no codes w/cheap Acutron scanner. I've tried pulling CPS & cam sensor connectors and reseating. Can't figure this one out. Would expect codes if by chance fuel pump or FPDM happen to fail. Car has 1/4 tank and had up on ramps to do pump job. Help !