ok my 95 monte carlo z34 3.4 started surging a few months ago so i figured it was time for a freshening i put 1 new cylinder head on new head gaskets ,timing belt,fuel pump and filter,tps iac valve checked for vaccum leaks,,none found,then i noticed that when it starts surging which is about 10 min after starting it,if i disconnect a vaccum it soumds like its running normal again.i dont get it any help would be great cuz i"m goin nuts tryin to figure this 1 out..and no its not air in the coolant i checked that to.

 

do you have check engine light?

 

cant retrieve any codes

 

Is the check engine light on?

 

no check engine light

 

Since you replaced the fuel pump (I am thinking fuel related) and you pull a vacuum hose off it runs normal. Did you replace the pcv valve? I'd suggest you recheck all your vacuum hoses. Those hose if they have never been replaced are 18 years old.

 

changed the pcv and checked the hoses well.they r mostly that hard plastic and r in great shape.the car just broke a 100000.just seems like its starving for air i even changed the maf sensor.and checked the air filter..both r good

 

As I understand it, you did all that work because of the same issue you still have? I was thinking at this point, although if it had the same symptoms before, if you could have an incorrectly installed intake gasket?

 

been workin on cars almost 30 yrs and i thought that and changed my intake gskts and plenum just to b sure.didnt help any

 

when the problem started i already wanted to do the head gaskets just because i knew they were due.then the timing belt had to come off anyway so i replaced it to then the fuel pump tps and iac were all done after in an attempt to fix this..boy i"ve never been stumped like this b4..thx for any help out there.i sure can use it