i think the smooth idle kinda rules out vacuum leaks , could be a sticking fuel pressure regulator mine used to feel down on power when cold it wouldnt miss it just wouldnt go fast when you gas it hard prob when it hits boost, you could feel the fuel pressure going back to normal when it straightened out mostly only within the first 4 minutes after start up on a cold morning, kinda felt like a car with a clogged fuel filter , i used stp gas treatment a few times it hasnt done it for years now