code 51/ quits when returning to idle

[professorbob]

I reinstalled the exhaust header gasket and ran the engine to create codes. Started engine and allowed it to reach normal operating Temperature. RPM was still up when I pushed the accelerator pedal and it dropped back to about 800 which is in range. Slightly rough idle probably because of the excess soot. Tried to increase RPM and it would work up to 2800 quit until it dropped back to 16 1800 then come back up to the throttle position of 2800.
Shut it down and checked codes. 41 Throttle Position Sensor TPS... From your previous post about being able to run the engine without the TPS, I unplugged and restarted the engine. With the TPS disconnected I now am able to get the engine to reve to 3500, although still a little rough, which indicates the TPS may be the main problem here. I did not want to go any higher on the RPM without a load on the engine.
Question. Will an aftermarket TPS work, or should this unit come form Toyota. Thanks for your input in the search for my problems.

Also still wondering about the light on the dash as per above.
Thanks
Prof.