In head small version held in place by a steel collar early 1200 water temp sensor can't buy after market sugestions

recheck water pump and thermostat --check and test fans -radiator flow --and for possible head gasket failure

This is common issue early sign head gaskets failure for EJ251 SOHC engine for external coolant leak. Second gen 96-99 with EJ25D is worst because when head gaskets failed, it's an internal leak that allows coolant and oil mix together in the combustion chamber to destroy engine.
You can drive it for at least 6 months or more as long as you keep top up coolant since the leak should be small at a slower rate leak. I drove mine for a while before change head gaskets. You're looking at `$1000-1200 job a dealership since you might as well change the timing belt, water pump, idlers while engine is pulled to replace head gaskets.

I just today actually fixed a similar problem in my honda my problem turned out to be the Timing belt was loose and not gripping to turn the water pump causing all sorts of problems with the cars temp. and water temp. including the fan not coming on, it sounds dumb but it worked for me just push on the belt and if it moves its loose. quick turn of a wrench and fixed.. Good Luck

The camshaft sensor is in the back head on the passenger side. Has an electrical connector. It is held in place with a small bolt with a 10 mm head. nothing special to do after replacing. There is limiter space, so be careful do not drop it. Make sure it goes in straight, you might put a little oil on the o ring to make installation easier.

I commend you on your tenacity. I guess the code is P0172. So you have metered air due the the MAP and IAT in combination and good engine coolant signal but still too rich and runs rough. It all points to a leaky fuel pressure regulator valve.

I would say that there must be a small track between an oil channel and a water channel in a cylinder head gasket. The oil pressure is normally more than the water pressure, so the fluid transfer is one way - to the water system. The track will be very small, so flow will only occurs when oil pressure is above zero. It's all it can be, I think.

If you have an A/C turn it on and the fan should run, if it doesn't run at this point you can try to turn it manually with the engine OFF. If it is stiff, there is a good chance the fan is bad. Another way to test it is to take the connector off of the coolant temp sensor and take a small paper clip with ignition in on position, but engine off and jump the two points together. If the fan kicks on at this point it is good and we just proved that the Computer recognized the CTS. If all of this passes the CTS could be bad or the connector that you just tested could be bad. That is a problem with Saturn's. If you decide that you want to replace the CST "do not buy an after market" Buy from Saturn on that part and of course if you replace the connector...that will be the only place you will get that, but the reason you don't buy an aftermarket CST is the computer doesn't recognize it and you will find your fan not coming on again when it gets hot.

the collar on the pipe has to slip down out of the pump. i had to put some wd-40 on the pipe connection because it was corroded up. then i used some channel locks to work the pipe out of the pump. when reassembeling, make sure pipe is all the way in the pump before shoving the collar back into place.