Hard start, cold start problem, rough idle

[Bryan Foster]

Listers,
I have had a couple of weeks of rough idle during cold start ups.  The car
will start easily, but then idle very roughly for 30-45sec.  After that time
it runs and idles very smoothly.  If I start it up and immediately rev the
engine to >2000rpm then it runs very smoothly, but if I was to let off the
gas and let the engine slow down to idle then it sputters and nearly
stalls.  When I rev it up right after start up there is a considerable
delay btw putting my foot down and engine response as if the mixture is way
off.   It seems to happen if the car has been sitting for >1 hour.  Not
necessarily a completely cold block.  Does this point to anything in
particular.  Leaky injector?

Thanks in advance,
Bryan Foster