[jcarter]

This is a bit OT, I have a 96 GMC Surburban(yes, my brother has a Cobra).
The Suburban wont start if it has been sitting for a few days or if the weather is cold.
New heavy duty battery, new alternator, new fuel pump and filters, new fuel distribution unit as one was leaking(or whateveryoucallit). Fuel pressure up where it should be.
But it takes at least 30 seconds for the engine to start, once it starts, it runs perfectly. Nothing else is wrong, no bad computer codes. 82000 miles
Have had 3 different garages working on it, and now its at a GMC dealership and they cannot diagnose the problem either.
Its obviously a fuel problem, but nobody seems to be able to fix it nor determine where the trouble lies. I even called GM in Detroit but they had no clue?
Any help would be really appreciated, and I know you all here are experts.
Thank you,
Jane