High Idle when TPS is adjusted correct - 90 s13

[Peabody]

I have had this problem for a few years. I am the original owner of my 90 s13. I have a new Jasper KA & have had the same problem with my original KA that lasted 225K. I know I should have swapped out the KA motor but it is a long story. The only mods I have are header, air intake, Performance ECM that I got back in 1993. At that time you had to buy a new computer with the new map and send in your original Nissan for a core. It cost over $700 but made a big difference in power. Also on this ECM I have no lights so I cannot check any codes. It sucks. OK my problem is when I adjust the TPS (I have a New TPS ALSO) to .45 volts the idle climbs to 1800 RPM's and will not go down when I adjust the Idle control valve screw. I also took the ICV off and cleaned it out. The only way to get the idle down to 700 - 800 is to take the TPS and turn it all the way to the right which is at .12 volts and not the .45-.55 that it should be set at. I think when the TPS is not set to the correct voltage it has to make other sensors or components not work well. Does anybody have any ideas on what I can check out. It does seem to run rich & I changed out the o2 sensor and that did not help. It started to run like this when I hit 200,000 miles but with the new Jasper long block it does the exact thing so it is not in the motor. I also removed the IAA years ago but that really has nothing to do with when the high idle started. I also have new fuel injectors. Someone said it could be the fuel pressure regulator causing the rich smell.THANKS FOR ANY HELP!