Having had a similar rich running problem - I would test the resitance of the temp sensor at engine cold and at warm - there is a range it works within and that would tell you if it is reacting to temp - finding whether it is in spec is tougher unless you remove it..but at that point I would just replace it. First check the fuel pressure regulator by removing the vacuum line going into it and looking or smelling for fuel - this part is easy to replace if it is bad - and problem is solved...another way to do this is to attach some fule like the to return end of the FPR and put that end in a portable gas tank - then when running the car you can see a stream of fuel at idle that would otherwise be returning to the fuel tank - if there is not a steady stream FPR could be bad - of course be cautious with fuel and running engine - (know safety methods..not knowing how experienced you are). Removing the ECT sensor takes some practice the first time around becuase it is under the manifold and tough to get at - but a 3/8 drive with a 10" extension can get to it.

The AMM is another cause for a rich car - and mine elluded me for months before I got another know good unit to swap it with. If the engine is running rough after running rich this long or the plugs are fouled and you will need to replace them after doing any repairs to set a base line standard for ignition - so you can also check to see if things are fixed by looking at them after running the engine. If you have a multi-meter you can check 02 sensor for rich/lean condition to diagnose the repair - all in the FAQ secionts

Good luck.