94 sierra tbi 350 hard start and stumble problem i think when cold

Hi guys i have a 94 gmc sierra 350 tbi and i have like a little hard start problems when cold but in this video start well... but not so cold in this video like -8 but when its -15 or more it craink like 2,3 more time and have a poor fuel economy some time and poor acceleration i change all plugs AC DELCO and wires rotor and cap and i go to a mecanic to set the timming of the truck after doing that is that a vaccum problem ?? and the truck loop when cold ... is that a faulty catalyc converter ? do a poor start and make the truck looop please i need advises thank you oh and sorry i touch a botton on my phone and shut down the video quickly .. PS:Love GM trucks long live chevy's