Engine popping

I just had a 350 rebuilt with mild cam and when the engine is first started a loud popping like a machine gun is heard from the exhaust until it warms up. Then the engine will not idle acts like fuel starvation.
New 600 Holley, Mallory Distributor bored 60 over.
Rebuild was done by a machine shop and they are stumped.

Any suggestions???

 

I suggest you first do a proper intro, then post this question on the main forum...... this one is for introductions only.