vacuum leak on a 96 GMC Suburban

[PaulRNielsen]

I am hoping someone here may help me with my issue. My 96 GMC Suburban had a radiator leaking. I replaced the radiator, thermostat, and water pump. Although the truck is not running hot anymore, I have a vacuum leak somewhere. This started as soon as I replaced the cooling system. I have tried to find it using brake cleaner fluid but have not had any luck. When the truck is at an idle it seems to be fine but once I put it into gear the engine idle fluctuates. Does anyone have an idea of where this leak may be or where to look?

 

[97sub]

I current have a leak between the block and the exhaust causing a similar issue. I plan to replace the gasket there after I get the o2 sensors replaced. Not sure if you have checked your exhaust system for leaks.

 

[theforce]

When I was changing the spark plugs on my 96' I broke a vacuum line that is near the radiator. It ran up to the valve cover on the right hand side. You might try that.