TPS Sensor issues

Just rebuilt a 89 lx 5sp car. I ran the car for a few weeks with no problem. I went to check the TPS sensor for ($H#@'s And giggles) only to find that it wat sitting at 1.8 volts. I took it down to 1 volt. Now the car runs amazing BUT, the check engine light comes on now about 20-30min into my commute for work. If i turn off the car it restarts without the light on, and it takes another 20 min or so for the light to come on, ECT. I took the car to a friends shop, he scanned the ecm only to find that the code was a generic for a bad TPS sensor. I replaced it twice with new ones. it keeps setting of the light. What should i do. PLEASE HELP
5sp
89lx
F303- cam
65mm Throttlebody
ported heads
3.55's
A/C that chucks ice cubes!
This is my D/D

I had 1.8 volts with no check engine light. I put it down to 1v then .9v and now I'm getting a check engine light. I just put it up to 1.5 volts and no check engine light. Btw I put on a brand new B&G sensor.