I think I may have the wrong or bad water temp sensor.
Runs awesome when first started and warms up, but after everything heat soaks (30 min or driving) it lacks power and seems to heat the exhaust up as the temp gauge stays normal.

Reading how the ecu changes the a/f ratio as the temp goes up, could it be like the choke it stuck on a carburetor engine ?
Or more likely the air valve under the TB the water lines go to ?
I've unplugged the other air valve and nothing changes.

Seems I've got it just about right but when actually driving it longer I still have this problem.

I assume the JB-Weld and or block off plate for the TB is what I'm going to try.
Been talked about before but I "think" the block off plate for the car will fit the montero ?

Also.. could I splice in a rheostat into the water temperature sensor and tell the ecu what I want and what runs the best at the time ? I don't think I got the right sensor, same plug but could be a different ohm ..
Factory supposed to be 2.5k cold and 290 hot.. from what my manual says.

91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.