hot start problem...?

I replaced my injectors with 5.0 injectors a while back but recently when starting it hot, it'll stumble until i drive about 10-15 feet and "clear" it out, then it runs fine again. I thought maybe an injector leaking down, by why only when hot? when started cold it idles fine. and like I said after driving for a few secs it seems to clear out whatever the problem is. has anyone ever heard of anything like this? and can I read the plugs to tell me which one might be leaking down?
thanks!

What year?

Some later models suffer from heat getting into the injectors and have a sheild fitted to stop what you have. I think you may just have a similar problem regardless on model year if the Ford ones are more sensitive to heat than the stock ones you had before. I run late model injectors but have a heat shield fitted under the intake to stop heat getting up into the injectors and also the intake for better performance. See my site on the write up about it.

its an 89

I tried to model your heatshield on my 89 but it would require removal of quite a bit to wiggle it under the intake, because of the fuel lines, steering shaft and assorted other stuff... and this has gotten a little worse, now occassionally will it not only start hard, but not start at all... it'll crank and crank, and the only way for me to start it was to hold gas pedal to the floor, figuring maybe it was flooding from a dripping injector...? this has got me bummed, but at least I think I finally figured out how to seal my valve cover positively.... woo hoo :wierd: