1995 GMC C6500 6.0L Gas (TBI): Runs rich on cold start

Truck runs rich for 2 - 5 minutes on cold start. Worse in cold weather (below 40 degrees). No CEL (yes, the CEL works). The engine stumbles, idles rough, and we can detect a slight raw gas smell at the exhaust. Clears up and runs fine after initial warm up and the problem does not return until following day.

Sorry, but we do not have a scan tool. However, we do have analog and digital volt-ohm meters.

Based on my research, I suspect engine coolant temperature sensor or oxygen sensor. I could only find 1 oxygen sensor; shouldn't it have 2 (1 for each bank)? Also, I cannot find the engine coolant temperature sensor; where is it located on this model truck?

Since we do not have a scan tool, I would like to test the ECT sensor with a VOM. Does anyone know where I can find a resistance - temperature table to help with our test?

Thanks.

Those tables are easy to find by googling what you are looking for.