new 350, not much power?

[DRobb's_85]

A few months ago I swapped the old 305 out in my 85 K10 4x4 and put a new crate gm goodwrench 350 paired to a new edelbrock 600 cfm carb in its place. The new 350 runs fine, but I dont think its running at its full potential. I mean, it feels just slightly more powerful than the old 305 that was in it, and Its almost like I can barely keep up with traffic. Also, the other night when a cold front came through, I was entering a freeway and gave it about half to 3/4 throttle and it bogged down for a second and then backfired (popping noise). It doesnt do this when it is relatively warm (anything over 55-60 degrees) only on really cold days. I know I shouldnt expect much as it is a heavy 4x4 but I need to at least be able to keep up with traffic lol. Do you think the carb just needs to be tuned or what. Any suggestions on what I could do to make it run a little better? Also, on warm starts (like 10-15 min after it is turned off) it is a little hard to start. I have to give it a little gas and it will crank for a few seconds, then I let it sit for a sec and crank it again and it will fire up. Any ideas what that could be? Someone reccommended I get a carb spacer? Anyways thanks