03 z71 mechanical issues help asap

[CrazyJesster]

so i have a 2003 z71 ive had it over a year an it has 157k on it.
now it has a cold air intake k&n and headers not sure what brand.
and ive not done anything to it the truck was like this when i bought it.

recently ive noticed the truck acting weird like when im at.
a redlight rpm tach will flutter and jump up an down kind of misses some i guess?

now sometimes like when im at wally world or where ever and turn to the left.
like to park or something the rpms will fall and it will die

tongiht on the whole way home at every light it would die. if i didnt keep foot on the gas when i stopped in the store an popped the hood lef t it runnin before it died just setting there in park it kinda sounded like it was bowin or suckin air around intake manifold could this be a vaccum leak

someone mentioned to me it could the the intake manifold gasket and.
that year 03 was famous for doing it btw its got the 5.3 in it sorry didnt mention it earlier

is this ture could this be the problem now my guages are all good oil pressuer etc good volt reading