Test coolant temperature sensor circuit at ECU connector.  Download 1980 EFI Book, run electrical tests.  Check FPR vacuum hose for fuel.  It should be dry.

Search "running rich" on the site and start reading the hundreds of threads about it.  Welcome and good luck.

 

I would also check all of the electrical connections in the below site, maybe one of them is super corroded and making trouble: http://www.atlanticz.ca/zclub/techtips/electricalconnections/index.html

Another possibility is the cold start valve is leaking or otherwise adding some extra fuel after it's supposed to be off. It's usually not the culprit, but easy to test, just unplug it, pinch the fuel supply to it, and go for a drive. Obviously the cold start enrichment will not work for this test, so it may run a little rough until you get the temps warmed up. Although in Dallas this time of year, not too much need for a lot of cold start enrichment. ?

As others have said, run the basic tests in the the FI manual & measure the CLT & IAT sensor resistance at the ecu connector. This will test the wiring connections all the way to the sensor. Next to the AFM vane, the coolant sensor and air sensor are the next largest contributors to determining injector pulse width, and the coolant sensor connections are a known issue for corrosion.

Len