Welcome to the forum.
If there is gas in the oil, then there is an internal leak. Intake or head gasket. Probably the former. And as it warms up, so the the gasskets, and probably so does the leak. I am guessing that if the temp sensor went, and you have fuel in the oil, the intake is the culprit, and the mixture of oil, air, coolant and fuel is forcing the truck to stall out. Might be time for some elbow grease and some seal replacements bud.