Hopefully this is something simple I am overlooking but... I have a 350 crate motor with no erg, edelbrock street performer, mild cam and a 4 speed manual. Once the weather got hot the truck starts to buck/shudder when starting from a stop. I have tried to lean out the carb with no luck. Could a vacuum leak cause this? It is also hard to start when it has been sitting for 15 or more min when it's hot outside. Does anyone have an idea? Thanks in advance

 

Forgot to add. Truck runs great once the throttle opens up. Or of I'm starting off from a roll

 

when you say hard to start, like it cranks slow? if thats the case it might be a timing issue. had a old s10 that was like that

 

It turns over fine. I just bought a vac gauge and set the idle mix. Running well now