Maybe the injector could give enough to make the engine run when hot--but ask it to richen up when cold--it couldn't do it---as for that- the cam position sensor --I gotta admit sounds like a good point also.
How many miles are on the car? The idea of trying to isolate the cylinder--have you thought about that---if the vacuum leaks are accounted for--it's gotta be something electrical--that can and will lead to lots of spots on these cars to start eye balling.