Engine stumbles when cold at idle

[CHayes]

Hey there all. Im at my uncles and he has a 92' ram W250 with the 5. 9 Long box reg cab 380k and still running strong. when he starts it it runs rough and gallops until it warms up. He has to put his foot into the throttle to keep it running. usually cycles the intake heater 2x before trying to start the engine. it has only done this since getting cold this fall. Like 20 degrees or below it will do it. we started it tonight @ 45 degrees out and it ran + idled fine. When taking off from a start (1rst or 2nd gear) it will stuble as well almost like you are driving a gas job and didnt rev it up enough before you let the clutch out. It does this at any temp. We were thinking there might be something messed up in the governor but not sure. Is there any way to check this? If the springs are broken? out of adjustment? This engine has the factory recalled injection pump with 100k on the new pump. Any thoughts on this would be greatly apreciated. Thanks Caleb