Vaccuum leak, 351W carburated.. HELP!

i do have a mustang, but this is bout my 1980 Stepside.
Just bout the truck runnin poorly,Its gotta 351W in it, Performer Intake, and Edelbrock Carb, i think its a 750carb., aftermarket cam but dunno what, new starter, coil, radiator
I set the timing dead on at 3500 full advance, but i can't get the truck to idle down, and i can hear the vaccuum leak.
I checked the carb gasket, and alot of the hoses, i think all of them. i checked the brake booster for leakin too, it was ok. Im sure it's a vaccuum leak, but is the intake gasket likely to leak.

The truck ran fine when i looked at it 2weeks prior, didn't hear as much a vaccuum leak, but idled and everything. then it got cold the day i went to look at it, and the guy said he'd bumped the timing for it to run better (i don't know why he messed with it, unless hesaid that to hide something) ne ways, it wouldn't idle the dya i bought it, and he drove it to my house... so i'd already paid,
I don't know if he coulda hotroded it before i came in that two weeks and blown the intake gasket or if that is even likely.???

Tips where to look plz?? or any thoughts... THANKS!

heres some pics, i checked the carb gasket, and that little thing too.

n.m. can't get them to work....sorry

already did that, only with starting flluid, and it make the truck idle up if theres a leak. ...it's on the R side of the engine, but im not sure, if it's by the intake seal. I think im gonna have to check the carb again.

Thanks tho, i'll check into intake to head/block.