It sounds like you still have some kind of fuel system restriction, or the vane pump in your IP has failed or is still gummed up with WVO. You might give it some time to run for a while on the diesel and get good and warmed up, and running a dose of Diesel Purge might help too, anything to free up whatever the cold WVO may have stuck. Heat is definitely your friend here, so getting the motor and IP good and warm is a good goal to start with. Hopefully the IP isn't hosed/failed mechanically, but given that the problem arose suddenly as the car sat overnight, I am still thinking it is something less major than that. Usually when an IP suffers a serious failure you get some warning beforehand -- either the car dies while driving or you start to notice some symptoms like harder starting, loss of power, etc.
Now that it is running on diesel, with the electric pump installed, will it still only idle or does it run normally, make enough power to drive around, etc?
You can leave the electric pump on there, as long as it is a relatively low-pressure unit (no more than 5-10 psi max). If the electric pump is serving as a band-aid for a broken vane pump or a restricted fuel system, the car will still not run correctly that way, but it will run. However -- it is possible that the reason it started and then died after you removed the electric pump is that an airlock got introduced into the system when you had the fuel lines taken apart (particularly likely if there was still some restriction in the fuel line leading up to the electric pump that it had been sucking against). Did you try to get it running again after it quit?
Sounds like you had a good running car -- it can be that way again -- don't give up on it yet!
