I have a 1992 12 v it has a new lift pump new ip it will start a run for 15 to 30 seconds and die. But if you crack injector line going to number six it will stay running. Not sure if I have a injector problem or what's going on. Not sure if related to same problem but it does not have any throttle to speak of

 

Couple of rough guess's, you are getting air into the system and it is bleeding out via # 6 line when you crack it.
When the IP was fitted did you get the indexing of the throttle lever right?
Cheers Steve

 

If it was sucking air wouldn't it run with any injector line racked open

 

#6 is the top line out on the pump, guess the air is going to the top of the pump and out the #6 line first.