What cause a 93 ford ranger 3.0 v6 to stumble during warmup after that it get up an go?

most likely it is carbon buildup on the intake valves, after the engine warms up, the O2 sensor compensates for it, then all is well. run some Techron in your gas (use Chevron Supreme to have a double dose) and drive it hard, that should make an improvement you can feel by the time the tank is empty!