When you replaced the TPS, did you readjust the new one to specs?
MIght want to read through all of this:
Likewise, when you set the timing, you need to jump the one connector before setting timing. Connector locations here:
You might try jumping the diag connector, sometimes there are codes there even without a constant check engine light.
Also, is your air flow meter in good shape, and no leaks in the intake tube between the AFM and the throttle body?
Definately go through and make sure all of the grounds are good. There should be a couple on the engine, and to the body. Make sure the ECU looks good, that its well grounded to the body.
Sometimes on those, due to the age of them, you get bad wiring connections that just go intermittant. The heat of the engine dries and cracks them a bit, especially where the hrness goes through the intake manifold under the plenum.
Myself, my 22RE was always fine. The only issues I had was poor running/stumbling/sputtering, due to ECU under water, and poor running due to water in fuel.
Here's a post similar, but never really resolves it: