Slant six dies in gear

Do you have a vacuum gauge? I'm guessing you might have a vacuum leak. You can pick up a cheap one at harbor freight.

950rpm is pretty high at idle. I think the factory setting is closer to 750rpm in park and should idle around 550-600rpm in gear. If the engine stumbles and wants to die when you idle it lower than 950rpm in park, that's a pretty good indication that you have a vacuum leak as long as the engine is warmed up and the choke is open.