rough on cold starts (timing)

Hey,
I got an 88 c1500 5.7. I have put a lot of work into that car, and Basically the only problem left is that when I start it on cold starts it is a little rough, and I think I can feel it misfiring a littel, but whenI drive it down the block it is fine. What can be causing this? (this only happens on cold starts) here is the list of a few of the new things I have put in:

Timing Chain and gears
Radiator
fuel pump
distributor, wires, plugs, cap, rotor
egr, & solenoid
IAC Valve
Electronic spark timing control, and the computer itself
oil pump

What can cause this.. I heard of a leak in the intake, but how can I test for that?

Thanks matthew

Well if your brave you can use the raw propane gas method, or another way is to spray carb cleaner around the top end gaskets (while engine is running) in either method you will get an increase in rpm when a leak is crossed by the gas or liquid.

no a leaking intake will give you a lot of drivabilty problems not just a cold start up problem.. Check the
Coolant temp sensor close to being out of specs. (tells the ecm it is warmer then it is)

I had an 88 full size jimmy with a 5.7 in it with the same problem and it was the base gasket for the tbi....... there was only a piece about 2" long left of it. once the engine warmed up it sealed around the tbi cause the aluminum intake expanded