What would cause a vacuum problem that makes my truck throw code 34

What is your question?

My truck keeps throwing a code 34 and 45 but I just replaced the map sensor and the tps. I also had the injector block replaced. 2 days ago it ran bad and smelled like gas real bad. Last night I replaced the tps and not the gas smell is better but it still runs bad. And both codes are now showing. I read that it was probably from a eratic vacuum problem. Can you tell me what might be causing this vacuum problem? It makes a kind of popping noise from the exhaust? I think. Any help would be great.... Thank you

What makes this problem better or worse?

I don't think it matters. It used to be when it was hot

How long has your 1994 GMC Sonoma had this problem?

A few weeks