my car's idle has been pretty messed up lately, it goes from 800 to 1000 and back. Also, I noticed that my boost gauge (which normally reads 17 vac at idle) goes from 17 to 15 and repeats. Do I have a vac leak?

 

COuld be a few things man,

Check all ur hoses *cracks., loose...etc
Then check ur TB gasket * rips

Then Could be ur IACV *located back of Inatke manifold

Or coul dbe ur coolant bypass, take ur TB off, and there are 2 coolant lines running through it. Take that peice apart and there is a white screw in there. Sometimes that plastic screw comes undone, and cause ur car to idle funny..

Good luck

 

that just happened to me on my 94' gsr. i found a small head gasket leak and decided to take the head off machined it so it was completely flat. replaced with a mugen head gasket and no more problems with a little more compression.

 

try all that to a good reply