New injector pump/problems

I have a 2000 dodge 3500 with 300k on motor and auto tranny. Recently bought a rebuilt injector pump and installed it. Works great except for having to give it a puff of ether to start. It will run all day and just yesterday had it over 80mph with no problems with fuel delivery. But when you shift it in to gear "automatic tranny" it try's to stall, also as soon as it stalls or you shut it off you have to puff ether in it to start no matter how long it has been running. Please help!!! Thanks in advance.