My K5 won't hardly idle when I come to a stop sign and the engine is cold. It's like the fuel line is kinked. I'm running the 5.7 TBI with HP heads. Once the engine is warm I can come to a stop no problem. Runs like a top. Wouldn't a vaccum leak continue regardless of the engine temp? Also, when starting cold, my temp jumps through the roof even with my flex-a-lite fans for the first few minutes and then calmly comes back to 210. Problem is I worry about it getting that hot every time I run it. Should I switch to a 160 degree thermo? Is there a reason not to? Finally, I get a "lean" code nearly every time I drive but the vehicle seems to be operating fine? Is this due to the aftermarket heads or what? Shouldn't the motor be running really hot if it's lean? I took it in when the "check engine" lean light first came on and they replace the fuel pump? Didn't make the light stop coming off though. I'll quit with the questions now.