Dead spot in throttle
 

I have an 02 GMC Savana 5.7 4L80E 3.73. I have replaced the fuel pump and filter. Done the central port to multi port conversion with a new regulator. Checked the cap, rotor, wires and plugs all looks fine there. It is not throwing any codes.
I have a dead spot in the throttle. When I go to accelerate it goes fine if I am light on the gas but as I increase throttle pressure the output does not equal the input. It goes flat for a good portion of throttle travel about 15% to 70% and then starts to equal out. I have no power at all ever. Not off idle or WOT or anywhere in-between. Heaven forbid I have to start off on a hill.
Does the TPS go bad on these? Can I put an OHM meter on it and what should it read?
I am only getting 8MPG. Can someone please help?