I just put a new radiator in my 95 4runner 3.0, 120K. No leaks, all is good on that end. But while I had the hood up, and the engine idling I heard a sort of popping rattle on the passenger side of the engine. When I revved it a bit, it went away, but then as the RPM came back dow, the popping rattle came back. Now the beast idles at about 1750. The only other thing I have done is one can of BG 44K about 400 miles ago, and a new tranny about 1K ago. I don't think the tranny did it, 'cos it ran fine until today. Might that fuel cleaner have caused a blockage? Am I looking at a vaccuum leak, or something worse? Any input is GREATLY appreciated.

 

I just listened really close and the noise is located towards the rear of the engine. The dashpot (?) vibrates when I put a finger on it. The vibration seems to coincide with the noise. How likely is this and is it a replace or adjust issue?

 

Okay, I just looked again and now I know the dashpot is in a nother location. So what is it that's bussing? The Air Suction reed valve? If it's this, is it a shop repair?