I know I have a small intake manifold coolant leak. Its coming out of the exterior of the engine and running down the back. Would this type of leak also cause my vacuum leak issues?

 

Doubt it, the coolant system doesn't have anything to do with the vacuum system.
That being said, the manifold may be leaking elsewhere & the vacuum does come from the port behind the throttle body.

Get some brake cleaner, let the engine idle & spray the vacuum lines. When the idle changes - you've found a leak. Also check the line to the vacuum canister ball thing (if equipped) or the canister in the DS fender well. Then the line to the cab & in the cab to the HVAC controls.

 

Thats Ironic though my neighbor picked up a 1998 jimmy cheap thats leaking the same way.The guy who sold it thought it was head gasket

 

it won't cause it, but may another symptom of the same problem. the plastic reinforced intake gaskets are quite brittle when they get older. make sure it isn't allowing coolant into the intake valley and contaminating your oil. it could have other cracks that are causing a vacuum leak.

 

In another amazing coincidence I bought my 1998 Jimmy from a guy who thought the head gasket was bad. I told him it was most likely the intake manifold gaskets but he didn't believe me. I got it for $1200.

 

Lol. I had to change the gaskets in my 96 about 2 years ago. 14 years it is!

 

thanks guys. I think i have isolated my vacuum leak to my HVAC system, i thought for a minute that it might be related to my 4wd issue. I did a number of tests after replacing most of the vacuum lines. Off to the shop to see if they can figure out this noise coming from my 4wd system. damn

my intake gasket doesnt leak too bad. i tightened the bolts a little about 2 years ago and it has been pretty good *knocks on wood*