if I have my water temp sensor disconnected (the one below the thermostat housing; mine broke) will it cause all rpm to be equally rich; or does that sensor only really effect idle or low rpm?

 

Yes, that sensor controls among other things the fuel enrichment at cold temperatures. I would assume the default value if the sensor is disconnected or faulty would tend towards the rich side so the engine will start & run even in the cold.

-=Russ=-

 

believe it sets the temp at 165 degs, so you should run fine around that point but bad above or below

 

The ECU defaults to 80degC (176degF), which is just below normal operating temp. The engine will run poorly when cold because it won't be getting enough fuel. It doesn't run rich.